I have two laptops, same model, one my wife's and one mine, and I'm using a Gigabit Switch to extend my Cat5 length. One cable works fine in my wife's computer, but in mine, the cable won't give me network access. Any idea why? The port works fine with other cables in the past.
Possible answers: the cable is crossed, one of the NICs has the auto commutation enabled te other no. Or just tolerances
Is your computer limited to 100Mb? 100Mb uses two specific pairs for upload and download so if either pair is damaged it won't work. Gigabit can use any of the 4 pairs in either direction so as long as there are 2 undamaged pairs communication can occur (but at lower speeds).
I had the same problem with one of my laptops. If I plugged the cable directly into the laptop, I had no internet access. The only solution that worked for me was to place a RJ45 network coupling on the end of the cable and a network patch cable from the coupling to the laptop. After that the Internet worked.
Just look at the plugs if the orange and green wires are in the same order your cable is straight, if they are swapped your cable is crossed. Just google for nice pictures
I've gotten flaky cables to work sometimes by changing the ethernet settings to 10 mbps/half-duplex (as slow as it'll go). Your mileage may vary. Check your local laws. Contact your doctor immediately if you experience side effects or sudden death from slow ethernet speeds. Keep out of reach of children. This post has been formatted to fit your screen.