I'm doing some rewiring. Several years ago I ran CAT-5e cable throughout my house. They terminated using standard wall plugs, on the other end to a patch panel (punch-down), which then patched into a gigabit switch (D-Link DGS-1024D).

This was a bit overkill .. I don't need the patch panel, and it created more space and clutter than what I really need, so I'm in the process of removing the patch panel and just capping the cable with standard RJ45 plugs, then plugging directly into my switch.

However, several times now, after I've done this, they only reconnect at 100baseTX, when they were connecting at 1000baseT before I capped.

What's going on here?

  • ask a friend that has a ethernet cable tester and have a look at your installation, maybe you missed a wire while capping.
    – vautee
    Apr 23, 2014 at 6:29

1 Answer 1


Make sure you get both the pinout and the pairings right. The right pins must be paired together in a twisted pair:

1 & 2
3 & 6
4 & 5
7 & 8

Getting the pairings wrong won't show up in a pinout tester, but it'll kill your ability to do 1000BASE-T.

  • That was exactly it. I was copying the pinout from a spare ethernet cable, which was White/Orange, Orange, White/Blue, Blue, White/Green, Green, White/Brown, Brown. That would work for 100BaseTX, but would not connect at gig speed. It works when I switched to: WO/O, WG, Bl, WBl, G, WBr, Br
    – desau
    Apr 24, 2014 at 16:25
  • @desau Glad I could help. By the way, that wiring wasn't even correct for 100BASE-TX, so I recommend you re-terminate that spare Ethernet cable to the correct pairings, so that it doesn't cause problems for you or anyone else in the future.
    – Spiff
    Apr 24, 2014 at 17:16

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