Gigabit speeds drop to 100mbs on any patch cord over ~1m in length

[myleskeeffe]

Hi Tomshardware Community,

We recently had installers come in and run Cat 6 to all the rooms in a house we bought. All the gear we have used is Unifi. Every room is able to get 1gbs speeds (over the local network) fine, except one. One room is able to get connection, but runs at 100mbs. I first thought maybe it was my computer, so I tried another laptop which I knew was able to handle 1gbs. It also reported 100mbs (both on its own and looking at the unifi switch). Next thinking it may be the cable I grabbed a spare ~1m patch cord and using the laptop, it was able to connect at 1gbs. Due to this room's layout, the computer wouldn't reach without at bigger cord. So thinking it must be the cable, I went to Bunnings and picked up an Antsig 3m Cat 6 Ethernet cable. I plugged it in and... we're back to 100mbs. As far as I know I have not enabled the "drop back down to 100mbs on any patch cable longer then 1m extending from the wall" option in the unifi controller. What other troubleshooting steps should I try? As it works with a smaller (and at that Cat 5e) cable, I don't think it was the installers fault - but I have no clue at this point.

While we only get 100mbs on the NBN through Aussie Broadband, we're planning on adding cache servers, plex and some other local network servers/file storage devices - and would really appreciate every device being able to communicate at 1000mbs. There is one error message/kind of I have found - which comes from the computer when I try to run diagnostics on the connection.

Specs
Computer In Room With Issues:
- x399 Taichi (Has dual gigabit NIC)
- Thread Ripper 1950x
- Latest drivers from support page

Network Gear/Visual Explanation:

Thank you in advance for any help!

 

[anotherdrew]

There is a 90% chance that the cable in the wall between Beast-Comp and your 8 port switch is damaged. It may have been stapled down too hard or kinked or pulled or something. I'd put 10% chance that you have a bad wall plate or something else. Sucks ... looks like a nice setup. Your contractor should have a test kit and I bet this line will come up as not quite up to snuff.

 

[myleskeeffe]

There is a 90% chance that the cable in the wall between Beast-Comp and your 8 port switch is damaged. It may have been stapled down too hard or kinked or pulled or something. I'd put 10% chance that you have a bad wall plate or something else. Sucks ... looks like a nice setup. Your contractor should have a test kit and I bet this line will come up as not quite up to snuff.

I took a quick look behind the faceplate on either ends of the cable - do any of these look like they could be causing the problem? If there's enough slack and it is just one of the connections sides - I might be able to replace the connection (with another keystone). But if it's in the line I might get the installer to come back. The second one looks like it could be causing interference (there's an electrical outlet about 5-10cm away), but I'm not entirely sure.

Thanks you in advance!

 

[anotherdrew]

Unshielded Ethernet (which yours looks like) should not be run in parallel with electrical wiring. It creates noise that will interfere with signaling (super short version ... google twisted pair for more info). They can cross, so if your electrical is run horizontally in the wall and the Ethernet is vertical, that's ok.

The kind of issue you are looking is very minor and may not be visible. It potentially only affects one pair out of the 4 in the cable.

 

[myleskeeffe]

Unshielded Ethernet (which yours looks like) should not be run in parallel with electrical wiring. It creates noise that will interfere with signaling (super short version ... google twisted pair for more info). They can cross, so if your electrical is run horizontally in the wall and the Ethernet is vertical, that's ok.

The kind of issue you are looking is very minor and may not be visible. It potentially only affects one pair out of the 4 in the cable.

As the installers have a relatively good reputation I doubt they crossed them, but I'll get them to come around to have a look. Thank you for your help

 

[anotherdrew]

I had a thought when I woke up this morning. The new cable you bought from Bunnings ... did you try it somewhere else on your network. It does not happen often, but sometimes even a brand new cable will be faulty. Sometime when you fixate on an issue you forget to check the obvious things.