100Mbps instead of gigabit LAN

csongiika

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Aug 14, 2016
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4,510
Hello!
I have a small network at home, I have two different cables going through the wall from the router to another 2 rooms.
My ISP just connected fiber optic and now I have a new modem and I should have a 300/100 connection. The problem is that I'm getting only 100Mbps link speed through the in-wall cable.

I have tested nearly anything I can think of. I've moved my computer to the router and tested by plugging in directly and it works perfectly fine, I've also tried each cable I have and all of them works at gigabit speed. I've checked the termination jacks at both ends of the wall and they are terminated correctly, all 4 pairs. I bought a cheap cable tester too, everything seems fine. I want to mention that all of my cables are Cat5e.

The only thing I can think of are the in-wall cable or the termination jacks, despite being terminated correctly. The weird thing is that at the other room the situation is the same.

My question is: can it be something else wrong, do I miss something? I think I'm going to change the termination jacks and if it doesn't solve the problem I think the cables are wrong, but I don't think the cables should be wrong.
 
Solution
That's long enough that you need to have decent cable and terminations. I'd try reterminating, making sure that you keep the pairs twisted as close to the terminals as possible.

csongiika

Reputable
Aug 14, 2016
2
0
4,510

Yes, I'm testing to the same port, I don't think they're configured differently. I had my PC connected to the router directly several times and it connected at gigabit link speed every time.

I only have this PC with gigabit network card.

The cable is something like 20-25 meters.
 
Your problem is likely that you bought a cheap cable tester...not that any normal person can afford the good ones for home use. Cheap testers only verify that you have connected pin1 to pin1 and pin2 to pin2 etc If you would not follow the standard color codes the tester would say it was fine but it would not work. But even if you put the wire colors in perfectly the wire may be slightly loose. It maybe good enough to light a led but not tight enough to pass data.

This happens to even professional installers which is why they pay the big money for a meter. For a home user all you can do is carefully try again and hope you get lucky.

Although you can do nothing to fix it you need to make sure the wire in the wall is not copper clad aluminum. It will generally say CCA on the cable but you can tell by looking at the wire many times because it is silver in the middle. This cable has massive issue being terminated correctly and does not run to the full distance. 25 meters though likely would be ok.