To troubleshoot a network cable test failed error, consider the following steps:

1. Check the cable connections
   

   Ensure the cable connecting the router or modem is properly connected to the device’s network port.

2. Check hardware configurations
   

   Consult the device’s instruction manual or user guide to verify the hardware is properly configured.

3. Check for interference
   

   If the connection is still not working, check for possible sources of interference. There may be device in proximity to yours that is disrupting the signal.

4. Check the port
   

   Check to see if the port and adapter are working properly.If the port is faulty, you may need to replace it.

5. Replace the cable
   

   If all other steps fail, you may need to replace the cable.