I am working in a small business, but the office is quite large. For ages, everything ran over Wi-Fi here, but it's simply not reliable enough (Walls blocking signal, high latency, etc).

Some days ago I started wiring LAN cables to everywhere in the office. Starting on the "main" TP-Link 16 port switch, I pushed longer LAN cables to certain places that are further away, and on certain points where more than 1 PC is, I bought TP-Link Switches (5 ports) and then plugged all those PCs to that switch.

Until then, I thought it was all fun and games, but testing the cables I noticed that I have no connectivity whatsoever. It seems that I cannot plug two switches together, because doing that does not allow traffic going through.

Strange enough, when I connect them together over a short distance, it works. I'm using a Cat5e cable (It doesn't have any shielding, just twisted pairs). Cat5e cables are made to work up to 100 meters. The LAN cables here are only about 20-30 Meters. Interference isn't likely the cause, because the cables don't run near electricity (only a very short distance, and there isn't even something pushing AC through. It's a wall socket - unused.)

With some searching I saw that "like" devices (same type) should be wired together with a crossover cable. I've done that and connectivity still doesn't work.

The cables are wired following way on both sides (If that matters):


Any help is greatly appreciated.

EDIT: It seems that the order of the colors made the difference. I rearranged it and now it works perfectly. Now I used this color arrangement: Standard Ethernet cable colors

Picture of the working network below:

LAN working fine

  • You probably need to get a cable installer to do this for you. Simple electrical connectivity is not enough for network cables. There is a full test suite for each cable category, and the equipment to do the testing is very expensive. A cable installer will install and test each cable, fix any problems, and provide you a full report of all the tests in the test suite for each cable.
    – Ron Maupin
    Commented Jul 3, 2017 at 14:11
  • @RonMaupin The problem is that I live in a country that we don't have any "qualified cable installed" near here, only in big cities maybe. I'm up to "myself and I" to wire this whole office together. Any help is welcome.
    – Fusseldieb
    Commented Jul 3, 2017 at 14:14
  • By the way, there are BICSI certified installers in Brazil ( and nearly every country in the world. See the web page for the BICSI CALA District. You may be able to find someone near you.
    – Ron Maupin
    Commented Jul 3, 2017 at 14:49

1 Answer 1


Are you properly connecting pairs (1-2, 3-6, 4-5, 7-8)? Based on your picture, you are not doing this correctly. You are not properly maintaining the pairs.

You must minimize what is untwisted.

Horizontal cable must be solid-core cable (maximum 90 meters), and it punches down to wallplates. Solid-core cable has better performance characteristics, but it is very fragile. It has a maximum pulling tension, and a minimum bend radius, and exceeding either of those can permanently ruin the cable. Horizontal cable is required to be run as a straight-through cable.

Patch cords should be stranded cable, and you need the correct connectors for stranded cable. The total length of the stranded patch cords in a cable run cannot exceed 10 meters (usually 5 meters on each end. Stranded cable has poor performance characteristics, but it is flexible. If you need a crossover cable (fairly rare since most modern equipment has Auto-MDX), then you do this as a patch cord at one end of the cable run.

A simple wiremap and electrical connectivity is not enough to guarantee that a cable will work. There are many performance characteristics that need to meet the specifications. It is easy to get a cable that seems to work, but it actually slows the network because of bad frames that cause retransmissions. The equipment to properly test a cable run is very expensive.

  • Thanks! I will redo the wiring, looking up pictures on the internet on how standard LAN are made (colourwise) and give you a feedback later. This picture should do the job: incentre.net/wp-content/uploads/2015/02/ethcable568a.gif
    – Fusseldieb
    Commented Jul 3, 2017 at 14:39
  • Solved! The colors made the diference, now it works fine. I edited the question also. Thank you =)
    – Fusseldieb
    Commented Jul 3, 2017 at 16:13
  • Some addition to Ron's strict "90 m of solid core and 10 m of patch": attenuation of stranded patch cable is appr. 20-25% higher than with solid conductors, so for every meter of patch more than 10 m you need to subtract 25 cm from total length. I've occasionally used decent quality patch cable over 25 meters and longer plus 15-20 m horizontal without a single error. That said, if you need to run high-power PoE, that's another story...
    – Zac67
    Commented Jul 3, 2017 at 17:18

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