I'm having a hard time getting my head around this! It ought to be simple, but ...

I have an internet feed at one end of my house with a small router/modem thing. From there I connect a Cat-5 cable leading to another room, where I cut the connector off and wired it into an RJ45 wall socket, and from there to a larger switch - this works fine. I also have another RJ45, connected to a cable that run over to another RJ45 - in one of them, I have connected the leads as in a cat-5 cable, that is pos 1 - 8 are Orange White, Orange, Green White, Blue, Blue White, Green, Brown White, Brown; at the other end they are twisted around: 8 -> 1, ..., so 1 s brown, 2 is brown white etc. It doesn't work, though, so I did it wrong. My reason for doing it this way is that you can buy these small connectors for connecting two cables - they are wired straight through, and when you connect them, you plug the cables in 'opposite' of each other, so 1 goes to 8 etc.

What is the right wiring?

  • \$\begingroup\$ here something that can help. Twisting cables of same pair is not reversing all cables .... See ethernet cabling standards. buy.advantech.eu/CMS/… \$\endgroup\$
    – Antonio51
    Commented Sep 20, 2021 at 17:13
  • 1
    \$\begingroup\$ The right wiring is to not swap the wires around. Pin-1 goes to pin-1, pin-2 goes to pin-2, pin-3 to pin-3, etc - always. The colors don't really matter as long as you keep the pairs matched - 1/2, 3/6, 4/5, 7/8 - but future-you (or someone else) would appreciate it if you followed the color standard. \$\endgroup\$
    – brhans
    Commented Sep 20, 2021 at 17:36
  • \$\begingroup\$ Research T568A/B Diagram. It doesn't matter if you use A or B, but stick with only one. \$\endgroup\$
    – rdtsc
    Commented Sep 20, 2021 at 17:50

2 Answers 2


Connect the RJ-45 jack so that the pins/wires line up with the plug end, i.e. pin 1 to pin 1, 2 to 2 etc. You should be able to look through the clear plastic portion of the plug and see which wires are crimped to which pins. Alternatively you can use a DMM on continuity mode to "buzz out" the pin/wire order before crimping on the RJ-45 jack and get the wires in the correct order.

These days most equipment supports Auto-MDIX so you shouldn't need any "crossover cable" type connections. Just use 1-to-1 straight wiring.


Not Really an answer but I done the same thing. the wiring is the same both ends but if I connect a through cable from the wall plate to a through cable both of the same configuration and then to a cable tester i get a crossover configuration, so do I connect from the wall socket to the router or gigabyte switch with a crossover cable/adapter or just use through ( T-568B ) cables throughout my system. Apparently the T-568A is the preferred wiring in Australia. Cheers


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