The Ethernet cable is a wired network connection that is plugged into a network interface card, which is located inside your computer. The connector on the other end of the cable is inserted into an Ethernet port on a local area network switch or hub. There are many reasons why it would not be detected, from being defective to simply not being plugged in properly. Here are some solutions for you to try before you need to buy a new one.
Check the connection
If you’re having trouble with Ethernet detection, the first thing you want to do is check the connection. The cable should be inserted firmly into both ends of the connector. You should also ensure that the cable isn’t broken or has been pulled out from one of the connectors. If you have a wireless router, make sure it is close to your computer and try using a different port on your router.

Verify that the cables work
A simple way to verify that the Ethernet cable is not just defective is to take it out of your computer and plug it into a different device. Then plug the other end of the cable into your computer again. If you are able to connect to the internet, then there is something wrong with the Ethernet port on your computer.
Check for driver problems
If your Ethernet cable is plugged in but not detected, the first thing you should try is to uninstall and reinstall the driver. If the problem persists, it may be that the cable is bad or defective. You can replace a damaged or defective cable by using a network cable tester to find out if the cable is still working.
If you don’t have a network cable tester, you can use a standard electrical meter to check for resistance on the wire. It should read anywhere from .5 – 1kΩ between all four pins on either end of the wire.
Change to another port
The first thing you should try is to use a different port on your hub. If you’re using a switch, plug the cable into another port on the network. If this doesn’t work, you can also try to use different connectors or cables.
Update your network card drivers
If you’ve been having problems with the Ethernet cable being detected, you should try updating your network card drivers. A faulty driver can prevent a computer from detecting an Ethernet cable when it’s plugged in. In Windows, go to Control Panel > Hardware and Sound > Device Manager and then expand Network Adapters. Find the Ethernet adapter and right-click on it to select Properties. Select Update Drivers, wait for it to update, and then restart your computer. If this doesn’t work, try installing a different network card driver or updating Windows’s default one by going to Control Panel > Programs and Features > View Installed Updates > Check for updates > Install if necessary > Restart your computer.
Reset your internet connection
It’s possible that your internet connection has been disrupted. To fix this, you can reset your modem.
Try a different cable
If you are having issues with your Ethernet cable being detected, try a different cable. The problem could be as simple as the cable being defective. It’s worth trying to see if the issue persists before buying a new one. Change the port that you’re using.
If you’re using an Ethernet hub, switch or router to plug in your Ethernet cables, then it might not be detecting your Ethernet cable because it is plugged into a different port. If that’s the case, switch the ports and see if that fixes the issue; if it does, then it means that there was something wrong with that specific port and not with your cable. Try powering off your computer and re-plugging in your Ethernet cable.
If you’re not getting any lights on your Ethernet connection, make sure you’ve turned off your computer and unplugged the power cord from both ends of the connection before plugging them back in again. Make sure both ends of the cable are securely inserted into their respective ports: one end goes into a network interface card (NIC) inside of your computer and the other end goes into either an Ethernet hub or switch or directly into an internet router. Check for damage to the connector on either end of the cable.