My Connection Speed properties are limited up to to 100Mbps instead of 1Gbps.

Router Model: TP-Link AC1200
Internet subscription: 300Mbps
Connectivity: Wired

Info: I have conceal my UTP Cat.6 cable via my wall and ceiling between Living Hall to Room.

So my situation is by sequence below:

  1. From the Router I am using UTP Cat.5e cable connected to the Wall Socket (the panel is stated Cat.5e).
  2. At the Wall Socket (Living), in between is using UTP Cat.6 cable from Living Hall to Room.
  3. At Room: I am using UTP Cat.5e connected to the Laptop.

Unfortunately, I just get up to 100Mbps at the Speed Connection.

I have tried to connect using same UTP Cat.5e directly from Router to Laptop and getting 1Gbps at Speed Connection perfectly.

Connectivity 1
Router -> UTP Cable Cat.5e -> Wall Patch Panel In-Out (using UTP Cat.6) -> UTP Cable Cat.5e -> Laptop Result: 100Mbps

Connectivity 2
Router -> UTP Cable Cat.5e -> Laptop Result: 1Gbps

I expected to have a 1Gbps Connection Speed in my Room via wired using Connectivity 1.

  • A common problem is that 10Base-T (10 Mbps) and 100Base-TX (100 Mbps) only require two pairs, so many cables (incorrectly) do not have or connect all four pairs, or they use two pairs for each of two connections. Unfortunately, 1000Base-T (1 Gbps) requires all four pairs, and it will negotiate to 100Base-TX if it doesn't have all four pairs. – Ron Maupin Feb 14 '19 at 3:03

You probably have split pairs in your in-wall wiring.

Decide between T568A or T568B termination for your in-wall wiring to use, and make sure both ends comply with whichever one you picked.

The wires connected to pins 3 & 6 must be a twisted pair. If you paired pin 3 with 4, and then paired pin 5 with 6, then you have split pairs. It's a common mistake. Split pairs defeats the ability of Ethernet's differential signaling to cancel out common mode interference.

Note that a simple pinout tester won't find this wiring flaw, because it can only tell which pins connect to which pins at the other end, not whether the wires in the middle where twisted together with the correct other wires.

Also make sure you have all 4 pairs (all 8 wires) terminated properly, and that you have continuity on all 8 wires. 100 Megabit Ethernet (100BASE-TX) only uses two pairs, whereas Gigabit Ethernet (1000BASE-T) requires all 4 pairs. So if you have pins 1, 2, 3, and 6 wired correctly, but problems with any of the other pins, that would cause 100BASE-TX to work, but 1000BASE-T to fail.


I would get a wire tester and test this portion of your setup:

Wall Patch Panel In-Out (using UTP Cat.6)

It looks like your simply getting Attenuation on the wire, so test the cable going from the Patch panel to your room. It might need to simply be re-punched.

  • Yup. And when you do it, check the split pair issue mentioned in Spiff's excellent answer. – ivanivan Feb 14 '19 at 3:05

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