Checking the network connection. How to check a network card? Making changes via the Command Line
The ability to obtain higher speeds depends on the bandwidth of the network equipment (network card and wi-fi router) to which the company cable is connected. Of course, it is worth taking into account the tariff you have chosen at which the service is provided, because... It also depends on getting the highest possible speed.
You can check the throughput of a wi-fi router by looking at its technical specifications.
How to check the network card bandwidth yourself? We will talk about this and give examples in this article.
The main verification methods for operating systems of the Windows family:
You can check the network connection status in 2 ways:
Option #1
1. In the taskbar, right-click on the network connection icon and select “Network and Sharing Center.”
2. Select the “Changes adapter settings” section on the left
3. Check the status of the "Ethernet" network connection
Option No. 2
1. Go to the Start menu and select Settings on the left.
2. In the window that opens, select “Network and Internet”.
3. In the Status section, select Configure adapter settings.
Check our connection status .
4. Select the Ethernet connection, right-click on it and select "Properties":
5. Click on the “Customize” button
6. Go to the “Advanced” tab and find “Speed and duplex” in the list. By clicking on “Value” you can see a list of parameters on which the network card can operate.
1. Go to "Desktop".
2. Hover your mouse over the lower or upper right corner of the screen, after which an additional panel will appear, in which click on the “Options” icon.
3. Go to "Control Panel".
4. In the window that opens, open "Network and Internet".
5. Open Network and Sharing Center.
6. On the left, select "Change adapter settings." 
7. In the window that opens, you will see the “Local Area Connection” shortcut
8. Select the local network connection, right-click on it and select “Properties”:
9. Click on the “Customize” button
10. Go to the “Advanced” tab and find “Speed and duplex” in the list. By clicking on “Value” you can see a list of parameters on which the network card can operate.
If you have 1.0 GB in your list, a speed of 200 MB/sec (more than 100 MB/sec) is available to you
1. Click on the "Start" menu, select "Control Panel".
2. In the window that opens, double-click on “Network and Internet” with the left mouse button.
3. Go to "Network and Sharing Center".
Windows 7: 4. Left-click on "Change adapter settings"
Windows Vista: 4. Left-click on “Manage network connections”
5. In the window that opens, you will see the “Local Area Connection” shortcut
6. Select the local network connection, right-click on it and select "Properties":
7. Click on the “Customize” button
8. Go to the “Advanced” tab and find “Speed and duplex” in the list. By clicking on “Value” you can see a list of parameters on which the network card can operate.
Sometimes this situation happens: you turn on the computer, but there is no Internet. And it’s a shame that yesterday he was definitely there, but today he’s no longer there! Of course, there can be a lot of options for solving network problems, but let’s consider the most standard example for practice. There is a system unit with a network card built into the motherboard, and a network card that is inserted into the PCI connector. Cable Internet, of which there are plenty now. Where should I start?
Let's begin.
1. First, we need to identify the network equipment. I repeat once again that in our case there are two network cards.
You can find out the network equipment with the command:
ifconfig
As a result, I received this command output:
eth0 Link encap:Ethernet HWaddr 10:bf:48:7e:3a:12
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
eth1 Link encap:Ethernet HWaddr 54:e6:fc:85:7f:76
inet addr:192.168.1.101 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::56e6:fcff:fe85:7f76/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:50872 errors:0 dropped:0 overruns:0 frame:0
TX packets:40181 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:53009700 (53.0 MB) TX bytes:6912325 (6.9 MB)
lo Link encap:Local loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:2674 errors:0 dropped:0 overruns:0 frame:0
TX packets:2674 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:292948 (292.9 KB) TX bytes:292948 (292.9 KB)
From this command we see that the system sees both of our network cards (eth0 and eth1), which means that they are physically working. You can also see the network equipment with the command:
ip link show up
Command result:
1:lo:
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0:
link/ether 10:bf:48:7e:3a:12 brd ff:ff:ff:ff:ff:ff
3: eth1:
link/ether 54:e6:fc:85:7f:76 brd ff:ff:ff:ff:ff:ff
The equipment is working, which means the problem is not in the hardware. Let's move on.
2. Let's check the operation of the equipment with the network using the ping utility. This is a program for checking connections on a computer network. It sends certain packets to a given node and receives replies from it, allowing you to indirectly determine the network congestion.
In order to check the functionality of the correct operation of network components in the system, run the command:
ping 127.0.0.1
The output of the command, which indicates that the packets are passing through normally:
PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.026 ms
64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.011 ms
64 bytes from 127.0.0.1: icmp_seq=3 ttl=64 time=0.029 ms
64 bytes from 127.0.0.1: icmp_seq=4 ttl=64 time=0.028 ms
64 bytes from 127.0.0.1: icmp_seq=5 ttl=64 time=0.032 ms
64 bytes from 127.0.0.1: icmp_seq=6 ttl=64 time=0.028 ms
64 bytes from 127.0.0.1: icmp_seq=7 ttl=64 time=0.033 ms
64 bytes from 127.0.0.1: icmp_seq=8 ttl=64 time=0.032 ms
64 bytes from 127.0.0.1: icmp_seq=9 ttl=64 time=0.031 ms
either by specifying your computer's IP address, which can be seen in the network connection information, or by looking at it in the output of the ifconfig command. In our case, the eth1 network card with the IP address is 192.168.1.101. This is the IP address of our computer.
ping 192.168.1.101
Command output:
PING 192.168.1.101 (192.168.1.101) 56(84) bytes of data.
64 bytes from 192.168.1.101: icmp_seq=1 ttl=64 time=0.043 ms
64 bytes from 192.168.1.101: icmp_seq=2 ttl=64 time=0.038 ms
64 bytes from 192.168.1.101: icmp_seq=3 ttl=64 time=0.033 ms
64 bytes from 192.168.1.101: icmp_seq=4 ttl=64 time=0.035 ms
64 bytes from 192.168.1.101: icmp_seq=5 ttl=64 time=0.037 ms
64 bytes from 192.168.1.101: icmp_seq=6 ttl=64 time=0.036 ms
64 bytes from 192.168.1.101: icmp_seq=7 ttl=64 time=0.017 ms
64 bytes from 192.168.1.101: icmp_seq=8 ttl=64 time=0.034 ms
64 bytes from 192.168.1.101: icmp_seq=9 ttl=64 time=0.034 ms
The second part of the test showed that the system works perfectly with network equipment.
3. “Ping” remote hosts. Let's run the command in the Terminal:
ping google.com
Command output:
PING google.com (173.194.113.197) 56(84) bytes of data.
64 bytes from 173.194.113.197: icmp_seq=1 ttl=58 time=13.5 ms
64 bytes from 173.194.113.197: icmp_seq=2 ttl=58 time=13.5 ms
64 bytes from 173.194.113.197: icmp_seq=3 ttl=58 time=20.6 ms
64 bytes from 173.194.113.197: icmp_seq=4 ttl=58 time=13.3 ms
64 bytes from 173.194.113.197: icmp_seq=5 ttl=58 time=13.3 ms
64 bytes from 173.194.113.197: icmp_seq=6 ttl=58 time=18.7 ms
64 bytes from 173.194.113.197: icmp_seq=7 ttl=58 time=13.6 ms
64 bytes from 173.194.113.197: icmp_seq=8 ttl=58 time=13.3 ms
64 bytes from 173.194.113.197: icmp_seq=9 ttl=58 time=13.7 ms
or you can specify a different host:
ping ya.ru
Command output:
PING ya.ru (213.180.204.3) 56(84) bytes of data.
64 bytes from www.yandex.ru (213.180.204.3): icmp_seq=1 ttl=55 time=29.6 ms
64 bytes from www.yandex.ru (213.180.204.3): icmp_seq=2 ttl=55 time=29.3 ms
64 bytes from www.yandex.ru (213.180.204.3): icmp_seq=3 ttl=55 time=29.5 ms
64 bytes from www.yandex.ru (213.180.204.3): icmp_seq=4 ttl=55 time=29.5 ms
64 bytes from www.yandex.ru (213.180.204.3): icmp_seq=5 ttl=55 time=29.9 ms
64 bytes from www.yandex.ru (213.180.204.3): icmp_seq=6 ttl=55 time=29.8 ms
64 bytes from www.yandex.ru (213.180.204.3): icmp_seq=7 ttl=55 time=29.4 ms
64 bytes from www.yandex.ru (213.180.204.3): icmp_seq=8 ttl=55 time=29.4 ms
64 bytes from www.yandex.ru (213.180.204.3): icmp_seq=9 ttl=55 time=29.7 ms
In our case, all 3 parts of the test passed “Excellent” and, accordingly, the Internet works. But if, for example, the problem was on the provider’s side (cable break, Internet disconnected for non-payment, power supply problems on the provider’s side), then the command output could be like this:
ping: unknown host google.com
And finally. If suddenly you cannot access only a certain site, for example vk.com, but access other resources normally, then you need to check the /etc/hosts file just in case. See more details. You never know.
With that, let me take my leave and good luck!
Don't know what network card is used on your computer? No problem! To find out, you don't even need to install third-party programs. Everything can be done using the tools built into Windows.
How to find out the network card model through Device Manager
The easiest way to find out which network card is on your computer is to use a tool called “Device Manager”. To open Device Manager, go to Control Panel, and then go to System and Security - System. Here, in the left side menu, there will be a link to “Device Manager”.
You can also open Device Manager using the command “mmc devmgmt.msc”. To do this, press the key combination Windows + R, in the window that appears, enter “mmc devmgmt.msc” and press the enter key.
Well, users of Windows 8 and Windows 10 can open the “Device Manager” by right-clicking on the “Start” button.
After opening the “Device Manager”, you need to open the “Network Adapters” section. There you can see which network card is on your computer. In our case, this is the integrated Qualcomm Atheros AR8152 PCI-E Fast Ethernet Controller network card.
It should be noted that in the “Network adapters” section virtual network cards created by various programs can be displayed. But, they are easy to distinguish from real network cards, since they are named by analogy with the programs that create them. In our screenshot (above), such a virtual network card is the Virtual Box Host Only Ethernet Adapter.
Using the command line to obtain information about network cards
The second way to find out which network card is on your computer is through the command line. To use this method, open the Start menu and enter the “CMD” command into the search. So you should open Windows Command Prompt. In the command line that opens, you need to enter the command “IPCONFIG / ALL” (screenshot below).
After executing this command, information about all network connections on your computer will be displayed on the command line. For each of these connections, the “Description” section will indicate the name of the network card that is responsible for this connection.
How to find out what network card I have using the msinfo32 command
Another option for obtaining information about a network card is the "msinfo32" command, which opens a tool called "System Information". To use this tool, press the key combination Windows + R and in the window that appears, enter the command “msinfo32”.
A broken network card will not allow you to access the Internet or local network if you connect to them through a network adapter. Network cards can be built-in or external. If the card is external, check to see if it is fully inserted into the slot. Also check the tightness of the connection between the network cable and the adapter connector. If these options don't work or you have a built-in network adapter, it's most likely a system settings issue.
If the Internet stops working. In the taskbar, check the connection status. If there is a red cross on the Internet access icon, then there is no connection. Try turning it on. To do this, click on the Internet icon and select “Network and Sharing Center.” Click on the red cross in the network connection diagram. This will launch a diagnostic program that will troubleshoot problems and enable the network adapter if it is disabled. Driver failure. If the network card drivers are installed incorrectly or they are damaged, you should reinstall them or make rollback to the last working state. To do this, click "Start", right-click on "Computer" and select "Properties" from the list of commands. From the menu on the left, open Device Manager. In the Network Adapters section, your device may show an exclamation point, which means it is faulty. Double-click the adapter, select the Driver tab, and click Roll Back.
and it is not visible in the device manager. Don't panic. If it worked properly before, you can turn it on again. To do this, in Device Manager, right-click on “Network adapters” and select “Update hardware configuration”. Plug and Play should immediately find your device and try to connect it.
Make sure that the problem is with the network card. If the diagnostics described in point 1 did not reveal problems with the adapter, it may be a problem with the provider or a technical failure on the line. Regularly update drivers and carefully store the disk from the motherboard - this will help you quickly solve problems with the network card. External cards can be tested on other computers to determine the cause of the problem.
In a pop-up window on the computer monitor, the message “Network cable is not connected” appeared, the LED on the network card did not light up. You insert and remove the RJ-45 plug in the hope of poor contact in the connection and realize that the cable is faulty. If you do not have a separate network card installed in your computer, and the network cable plug is inserted directly into the motherboard, the LED will not light if the connection is disabled by software.
A shutdown can occur without your direct participation, for example due to unstable network voltage, running unlicensed programs or a virus. To check in Win XP you need to go to: Start / Settings / Control Panel / Network Connections and make sure that the connection is connected. Less often, but it also happens, the network card driver does not work correctly. You can check: Start / Settings / Control Panel / System / Hardware / Device Manager / Network Cards. There should be no warning signs.
Network cards very rarely fail; this sometimes happens after a severe thunderstorm. You can check the functionality of the network card by connecting it to a known-good line or installing it in another computer, not forgetting to install the driver for it. Sometimes it is possible to get a network card to work by moving it to an adjacent slot on the motherboard.
A call to the provider's technical service will help check the functionality of the line on their part. If everything is in order with the computer and the provider, it means that the twisted pair cable has failed and requires repair. You can, of course, call specialists and wait, but if you wish, it is possible to diagnose and repair the twisted pair cable yourself.
The most likely malfunctions of the twisted pair cable are:
- complete break of one or more wires - occurs often;
- a short circuit between the conductors of one twisted pair or between the wires of adjacent pairs is less common.
Program for checking Internet access
Network Traffic Monitor
Search engines often search for the answer to the question: “a program for testing twisted pair cables.” A computer with Windows installed already has a program that displays the message “The network cable is not connected” if the twisted pairs in the cable are broken or shorted. You will have to look for the location of the break or short circuit yourself; there is no program that would indicate the exact location and cause of the malfunction. There are special testers for this, for example MicroScanner Pro.
It’s another matter if there is a connection to the Internet, but it is not stable or the download speed has suddenly dropped. To monitor network traffic, there is an excellent free program, or rather a utility called Network Traffic Monitor.
It allows you to measure data transfer speed in real time, observe changes in speed over time, save data on a hard drive, rubber windows, extensive customization options and many other useful services. Supports many languages, including Russian.
Installing the program on your computer is simple, just run the EXE file and press the confirm button several times. Network will automatically be added to startup and will monitor and save all data. To display any of the windows on the monitor screen, just right-click on the tray icon and select the desired window. Network Traffic Monitor is the best utility for analyzing and diagnosing network quality that I came across during my search. I have tested the functionality of the Network Traffic Monitor program with Windows HP and Windows 7. You can download the Network Traffic Monitor program with one click from my website.
Diagram of connecting a computer to a network
UTP twisted pair cable
To check a twisted-pair cable, it is advisable to competently imagine the electrical diagram of how a twisted-pair cable connects a computer’s network card to other devices, a hub, a switch or another computer. The figure shows a diagram of a section of the network connecting a computer to active equipment, a hub or switch.
To check the twisted pair cable, the part of the network card or hub circuit to which the RJ-45 twisted pair cable connector is connected is of interest. As you can see, each pair is connected to the transformer in a symmetrical circuit (a tap is made from the middle of the transformer winding, which is connected to a common wire, sometimes through a resistor or capacitor). Thanks to this connection, all induced noise in the cable arrives at the input in antiphase and is mutually destroyed, while the useful signal arrives in phase and its magnitude does not change. The transformer circuit has another advantage: it protects active equipment from short circuits and entanglement of wires in a twisted pair cable when connected.
Range and shape of the information signal
twisted pair cable
Some people have a question, what shape and scope does the signal in twisted pairs have? The photograph shown is an oscillogram of the information signal. On twisted pairs, both Rx and Tx signals have approximately the same shape and a swing of about two volts. The signal is transmitted via one pair, and received via the second, which is why two pairs are needed for communication. If one of the RJ-45 connectors of the twisted pair cable is removed from the equipment, signal transmission automatically stops.
Theoretically, the signal in a twisted pair cable should have a rectangular shape, but since there is capacitance and resistance of the conductors, the signal shape is rounded. For this reason, the distance between communication points is limited, usually no more than 100 meters. The 2 V signal is not dangerous to humans, nor is a short circuit between pairs dangerous to network equipment, so you can troubleshoot a twisted pair cable without disconnecting it from the network. The network card, switch or hub will not fail.
How to find a break in a UTP twisted pair cable
There are several ways to find a break in a twisted pair cable: external inspection, continuity testing with a multimeter or pointer tester, and folk methods.
Checking the twisted pair cable by external inspection
Checking a UTP cable should begin with an external inspection of the cable along its entire length; special attention should be paid to the quality of crimping in RJ-45 plugs. If crimped carelessly, the conductors may not be inserted into the plug all the way, and the contact will be poor. Or the conductors overlap with each other at the point of fixation (this happens with the green pair, since its conductors are crimped at a distance of two contacts) and the twisted pairs can short-circuit in this place. If a visual inspection does not reveal a fault, then it is necessary to test the twisted pair cable.
If you had at your disposal a modern cable tester with an LCD display, for example, MicroScanner Pro, which allows you to determine not only the type of defect in a twisted pair cable, but also its location, or at least a homemade LED tester, then no questions would arise. However, in everyday life you have to make do with improvised means.
Checking a twisted pair cable with a tester or multimeter
The easiest way to check is to test the orange and green twisted pair with a pointer tester. To do this, you need to remove the RJ-45 plug from the computer's network card. Next, with the probes of the tester turned on in the resistance measurement mode, first touch the orange and white-orange conductor of the twisted pair. The tester should show a resistance of 1-2 ohms, then to green and white-green. The resistance should also be 1-2 Ohms. The polarity of the tester connection does not matter. Next, the resistance between the orange and green conductors of the pair is measured. It should be more than 100 ohms, usually equal to infinity. If the measurement results correspond to the above values, then the twisted pairs in the cable are working.
Here is another method, more complex, but reliable and indispensable if the twisted pair network cable being tested is not connected to the equipment. You need to bring the ends of the cable with RJ-45 plugs into one place and ring the conductors. It is necessary to set the switch on the device to the resistance measurement position and, according to the diagram, check the integrity of the conductors and the absence of a short circuit between them.
The photo shows a twisted pair cable crimped into an RJ-45 connector according to color-coded option B.
The end of one probe of the device is touched to the contact of one RJ-45 plug, and the other probe is touched to the contact of the same name of the second plug. The resistance should be zero. The wires of each color are called in turn and each wire is checked to ensure there is no short circuit with any other. The test for short circuits is carried out on one plug. To do this, one end of the probe is connected to contact, say number 1, and the second in turn to all the others. Next, the probe is connected to pin 2 and in turn to 3, 4, 5, 6. Since only two pairs are involved in signal transmission (orange and green, plug contacts 1, 2, 3, 6), you need to pay attention to them when checking Special attention.
But it is not always possible to connect the UTP cable connectors to one point. In this case, it is difficult to do without additional devices. Of course, you can extend the end of the tester probe to the entire length of the cable and perform the test together, or cut off one of the RJ-45 plugs, strip the wires and twist them together in pairs. But it is more expedient to make a simple device from an RJ-45 socket, short-circuiting the pairs in it with pieces of conductors with a diameter of 0.5 mm or resistors, as shown in the photo. It is better to use resistors, as this allows you to check not only the integrity of the twisted pair conductors, but also the presence of a short circuit between them. If the measured resistance value is zero, and not the value installed in the socket, it means that the conductors are shorted together. It is better to take different resistor values for twisted pair jumpers, for example 50, 100, 150 and 200 Ohms. Then the measurement results will be more informative.
The RJ-45 plug of one end of the twisted pair cable is inserted into a socket with jumpers, touching the tester probes to the contacts of the second plug, and checking each twisted pair in turn to ensure there is no short circuit between adjacent pairs using the technology described above.
Thanks to different resistance values, it is easy to check the correct crimping of twisted pairs when checking a newly manufactured cable. If any pairs are swapped, then the magnitude of the resistance will immediately show this. For example, if, when checking the orange pair, the multimeter shows a resistance of 100 Ohms instead of the required 50, it means that instead of the orange pair, another pair is crimped into contacts 1 and 2 of the RJ-45, or the cable is crimped in a different way.
It is very inconvenient to check a twisted pair cable by touching the RJ-45 plug. If there is a free RJ-45 socket available, the measurement conditions can be improved. Insert the other end of the cable into the socket and take measurements by touching the probes to the contacts inside the socket.
Based on the results of the inspection, a decision is made on further actions. If the orange or green pairs are broken or shorted, then you can replace them with one of the unused ones, brown or blue, if they are working. To do this, you will first have to cut one plug and ring all the pairs again, then the second one and re-check the pairs, since a break or short circuit may be in the plugs themselves. Short circuits occur at the point where the cable is clamped by the clamp in the plug when the wires are improperly prepared. Break if the conductors are cut when cutting the outer sheath of the cable. This is where they often break. If, after cutting the plugs, all pairs turn out to be defective, you need to more carefully inspect the cable along its entire length; if the damaged area cannot be detected, you will have to replace the twisted pair cable with a new one.
Checking UTP twisted pair cable without devices
If you don’t have a tester or multimeter at hand, you can check the serviceability of the twisted pair cable without them using the proposed method below. It is necessary to cut off 10-15 cm pieces from the ends of the cable along with the connectors. Release the ends of the cable from the sheath by 5 cm and remove the insulation from each wire to a length of 2 cm.
Pour a little water with table salt dissolved in it into a small container made of dielectric material (glass, plastic, plastic bag) at the rate of a quarter of the volume of salt from the volume of water. The more salt, the better. Salt is added to water to reduce its electrical resistance. Immerse all conductors of one end of the cable in a container with solution. You can immerse each twisted pair one by one. The distance between the twisted pair conductors should be minimal, but they should not touch.
The twisted pairs of the opposite end of the cable are connected in series to the poles of any battery or power source with a value of more than 3 V. If the salt concentration in the heated water is very high, 1.5 V will be sufficient. This voltage is produced by any AA battery, for example from a TV remote control. A battery from a cell phone will work well; it has a voltage of about 3.7 V. A battery from the motherboard will also work, it has a voltage of 3.2 V. If you have a 50-100 Ohm resistor, it is better to connect the battery through it to protect the case of short circuit of twisted pairs. The polarity of the connection does not matter.
The telephone network can be used as a power source. The voltage in the telephone network is about 40 volts and the current is constant, limited at the telephone exchange to 40 mA. This connection is safe for humans and the telephone line. This option is convenient to use if you need to supply voltage to a twisted pair cable in a hallway where there is a telephone box nearby.
Any charger from a cell phone, a USB port on a computer, will be suitable for testing; there is 5 V at the outer terminals. It is not permissible to connect to USB without a current-limiting resistor; you can damage the computer. To test twisted pairs, a current of 2 mA is sufficient.
After applying voltage, the following picture will be observed at the opposite ends of the twisted pair, which are in water.
As you can see, on the conductor that is connected to the minus (cathode), small white bubbles of hydrogen are released, and on the conductor connected to the plus (anode), yellow-green bubbles of chlorine are released. It is obvious that the pair is fine and there is no short circuit with other conductors. In the event of a short circuit, depending on which wire, white or yellow bubbles also came from the other wire.
If damage is found, then you can finish checking the twisted pairs and replace the faulty twisted pair with a blue or brown one. For example, when checking twisted pairs, a break was detected in the orange pair. Then connect the orange pair coming from the connectors to the blue pair of the cable. The connection technology is described on the page “Extending twisted pair cables”.
Of course, it is better to crimp the cable with new connectors rather than splice it. Or crimp using the old method, described on the page “How to crimp an RJ-11, RJ-45 plug onto a twisted pair cable.”
If the orange and green pairs are ok and you don't want to bother with crimping the connectors, you need to check the cut pieces of cable with the connectors. To do this, all colored wires of twisted pairs, stripped of insulation, are twisted together and separately the white and colored ones.
The connector is immersed in a saline solution to such a depth that the contacts are completely submerged in water. Twisted wires are connected to the battery.
On four of the eight contacts, white bubbles should form one after another. When you change the polarity of connecting the battery, bubbles should form on the contacts on which they did not appear before and also strictly after one. Deviation from this immediately indicates a malfunction. For example, if there are no white bubbles on one of the contacts, then the wire is broken; if there are no white bubbles on any contact, then there is a short circuit between the conductors. To clarify, you can perform individual testing of pairs by unwinding previously made twists.
Depending on the results obtained, you will have to crimp or splice the wires.
Checking a twisted pair cable using a potato
The cable is prepared as described above, only the container with the saline solution is replaced with half a potato. Each pair is stuck sequentially into the potato to a depth of 1-1.5 cm. The distance between the conductors should be minimal.
As you can see in the photo, the wire that is connected to the positive terminal of the battery turned green around the wire, and white foam appeared around the negative terminal. When the wires are removed from the potato, you will notice a darkening of the wire to which the minus was applied. If there are no changes in the cut of the potato, it means that the twisted pair conductors are broken or shorted to each other.
Just for fun, I poked the wires into the slice of an apple. Not so obvious, but it is obvious that the wires are in order.
Using the described twisted pair testing method, you can check wires of any type, cross-section and length.