An easier way to test your network cables is to replace them. If you don't notice any difference even after replacing the cables, it is safe to assume that the cable is not faulty so you can move ...

How to fix the PXE-E61: Media Test Failure, Check Cable Error? Faulty network connection If the PC needs to boot on a network device, you should check if the network cable is disconnected or faulty.

Don't be afraid to get out your drill, but there's usually an easier to run your network wiring. It's often noted that one should use plenum rated cable for runs through air conditioning ducts.