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Question Ethernet speed on router, and on a switch


Jun 28, 2014
I have a really bizarre problem here, I ran a cat5e cable from my PC to the router which is about 50m away, however it wont connect unless I set the speed at 10 Mbps, I thought there is a problem with the cable for sure, I re-did both endings with the same result, so I might as will change the entire cable, so I got a cat6 cable this time, same exact result 10 Mbps only.
I had an old switch laying around which has (10/100mbps ports) so I tried running it and put it next to the router, with the same exact cable (cat5e) and I got 100 Mbps speed.
Is there any reason on why this is happening ?
My router is TP-Link Archer C50, which supports 4x100mbps LAN, and I can see the full 100mbps on the router page when I connect the old switch to it directly.
What does the cable say on the side of it.

Most cable should be marked EIA/TIA certified. It should also tell the wire size and type of wire.

The so called "CAT" names have been abused by the fake cable manufactures.

Be very sure your wire is pure copper with wire size 22-24. There is a lot of CCA cable on the market and that flat cable. Neither of these are actually ethernet cable... or at least they do not meet the requirement to be "certified" as ethernet cable.

Then again if you have proper cable it likely is just that you do not have enough practice putting the ends on. It takes a number of attempt to get good cables when you are first starting out. Be very sure to follow one of the standard color patterns
The electronics actually have no idea what color the plastic on the wires it. Both ends must be the same though.

568a and 568b historically have been used. The brown and blue pair in really old cat5 cables (ie not cat5e) used to have fewer twists. They use those pairs to carry voice and the green and orange pair to carry data. So at those times the only patterns that would work were the 568a and 568b

With modern cables the wire pairs are the same number of twists no matter the color. You could use the brown pair in say positions 1,2 rather than 7,8 and it would work fine as long as both ends are the same.

What is extremely important that you keep the 2 wires that make the pair up...ie the one with the corresponding white stripe..together. If you were to cable pin 1 as orange solid and pin 2 as green solid on both ends a simple cable tester would show the cable was correct but it likely would not function. The wire pairs and the way they are twisted together are extremely important in their ability to carry data.
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Dec 11, 2013
To expand on bil001g's explanation: The pairs aren't 1-2, 3-4, 5-6, 7-8, they are 1-2, 3-6, 4-5, 7-8.

The center pins on a rj-11 (4-pin) phone plug is line 1 for telephones. Line 2 on a telephone is the outside connectors on a rj-11. So, if you plug a telephone rj-11 into a rj-45 jack, both line 1 and line 2 get a pair - line 1 = pins 4&5, line 3 = pins 3&6.
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