I have a single ethernet run at home that I just added. I have a cable tester that tests for pin/pair crossover or miswired pins. The entire line tests green (all 4 LEDs light up green on the tester) but I can't get any PC to connect through the link. No link light on the ethernet connection.

Any simple tests/fixes, or do I rip out the wall sockets and do it again?

migrated from serverfault.com May 13 '10 at 16:53

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Check that the pinouts on both sides are correct. Each pair might be good in the el cheapo tester, but if they aren't pinned out correctly you obviously won't get link.

  • I'll double check.. that's a good point. – Simon Gillbee May 13 '10 at 16:49

Also, you need to make sure that your ethernet ports on the PC and switch are indeed working.

  • The router and PC were connected via patch cable directly. The only difference now is that there is an attic run in between. – Simon Gillbee May 13 '10 at 16:48

If you are not connection to a switch, hub, or router at the far end you will need a crossover somewhere in the line. After you have plugged in at both ends see if either end lights up. Also try plugging in to the uplink port on the switch as this will often work with or without the crosssover.

  • One end of the connection is a PC. The other end is a wired/wireless router. Two devices used to be in close physical proximity to each other and were wired together with a simple patch cable. The only difference now is the new through-the-attic run with wall plate terminators at each end. – Simon Gillbee May 13 '10 at 16:46

Okay, let me get this restated - you used to connect using a patch cable directly to the wired port on the router directly to the wired port on the computer. The computer moved. You ran a wire from point A to point B with wall plates on both sides and used patch cables on both sides but don't get link.

Quick test: Disconnect router. Bring both patch cables and router to the computer. Plug the patch cables to the computer and plug into router one by one - do you get link? If not, patch cable bad.

If not this, then is it possible your router has an uplink port or something like it and you are plugged into uplink port?

What color codes are you using for the attic run?

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