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A PC no longer recognises a LAN cable if, for example, the energy saving settings were saved incorrectly. However, it is usually a defect in the cable that is responsible for the problem.
PC does not recognise LAN cable because of cable damage
If the LAN cable suddenly stops working, check the cable for possible damage.
- It is difficult to see a broken cable from the outside. It causes the computer to no longer recognise the connected LAN cable.
- You can detect a defect in the LAN cable by connecting it again with a different cable. If other cables are detected, you should replace the defective LAN cable.
- A hardware defect can also occur in the LAN interface, for example due to exposure to moisture, shocks or a fall of the PC. A new LAN interface is not expensive and can be replaced yourself.
- A working LAN cable can also be connected to the computer via USB using an adapter until the defective interface is replaced.
Energy saving settings in the system
If you change the values to save energy, a LAN connection may suddenly no longer be recognised by the PC. Here’s how to fix the problem:
- After a reboot, a LAN cable is recognised by the PC again in some cases.
- In the properties, under Power Management, you can specify whether the LAN connection can be disabled by the PC to save power.
- Uncheck the box to turn off automatic disabling.
- Reset your network adapter and check if the LAN cable is now recognised by the PC again.
- If the settings in the firewall are incorrect, a LAN connection may be obstructed.
- Some LAN cables are reliably recognised by the PC again after a driver update.
- Often the last resort is to completely disable all power saving options if the LAN cable is simply no longer recognised by Windows.
