Cat 5 dirty little secret

I just got a 2nd access point working at home.  It’s about 50ft away from the existing access point.  I had this working before, but replaced the main router (replaced dLink with Belkin) and it stopped working.

I was able to rule the problem down to a cable running about 20ft from my main router to the 2nd router.

  • If I plugged the 2nd router into a 4ft patch cable it worked fine.
  • If I plugged the 2nd router into the 20ft cable it didn’t work at all – no lights on either router, no ping response, nothing
  • If I put a continuity tester on the 20ft cable it showed all 8 wires were connected in the right order.

So – Short cable worked fine – long cable didn’t work at all.

After much research and a call to Belkin (who said 15ft is the max cable length) I solved the problem.  It boils down to what I consider a dirty little secret of network cabling:

When creating a cat5 cable you must wire the ends such that twisted pairs end on specific pins.  It is not enough to just get the two ends wired the same. Pins 1&2 must be a twisted pair and pins 3&6 must be a twisted pair.

Here’s the dirty part:

Those are the only 4 pins you need to hook up.

What it means is you wire both ends something like this

Pin1: Orange Wire

Pin2: Orange & White striped Wire

Pin3: Green Wire

Pin6: Green & White striped Wire

And you leave the rest empty.

More info on 1000bast T cables (which need all 8) at this link.

I know I have asked network guys and cable pulling guys specifically if there were any tricks to wiring the plugs, because I suspected something like this for a long time – and they all refused to tell me.  I vaguely remember one or two of them having an evil grin when they told me this.  Job security?  Maybe.  It was hard to learn, it should be hard for you to learn kinda thing? More likely.


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