Home wired network not going at full speed

I’ve got cat 5e cable across the house, and until now I thought I was going at gigabit speeds but realised that only the link between one switch and the router is actually gigabit… the rest of the house is going at a mere 100mb… even a brand new PC built with a gigabit ethernet adapter connected to the switch that’s connected to the router.

Another switch that’s connected to the aforementioned switch isn’t going at gigabit either…

What can I try?


Brand and model of the router? And of the switch that the PC is connected to?

Router: CG7486E Wireless Gateway
Switch: Dlink GO-SW-8G

I’d have sworn I’d seen it at gig speeds in the past…

I just redid the connectors and I’m pretty confident they’re well done…

Could it be due to interference from nearby electric cabling? Just a thought…

Very unlikely to be frequency interference from physical cables. There’s a small possibility that could cause drop outs, but not slow the speed generally.

What are you using to test the speed?

  1. Visually seeing the switch lights in 100Mb mode.
  2. Visually seeing Windows tell me it’s connected at 100Mb.
  3. Logging on to www.speedtest.net and seeing that I only get 100Mb max when I pay for 300 (granted this would be for internet only, but still it’s an indicator… is it not?)

Only thing missing would be to connect a USB to my router and try to set it up as a NAS and transfer a file… but not exactly sure how to set it up… so I’m staying out of that for now…

Oh, and I just changed the cable to the router itself (which if I’ve not been lied to has 4 gigabit ports) and Windows still says 100mb…

Good to know!

Right… it’s gotta be the cable… I just tried with a laptop with both the same cable as the PC and a new one and sure enough, with the new one 1gb, while with the old I was stuck in 100mb…

1 Like

Not too surprising. Gigabit Ethernet uses all 8 wires (4 pairs), while 100baseT only uses 2 pairs; if any of them are not connected properly or if there are any errors negotiating gigabit, most interfaces will fallback to 100mbps (or sometimes even 10mbps).

Also, some pre made (100baseT) cables may only have 2 pairs connected, which can’t handle gigabit traffic.

1 Like

I experienced something similar, it turned out to be the switch that is plugged into the router that became the bottleneck. If you have another one, try switching it out.


I’ve had the same thing. One of my forgotten switches was the bottleneck. Switching it to a a Gigabit switch speed everything up.


Doh! So that might be it… I re-did a connector… “forgot” to do the other end… that must be it…


Right… so I re did both connectors… and the wire seems to be ok… but it’s still going at 100… insteado of gigabit… ugh… any other ideas?

all switches in the network are gigabit… and the links between them are going at gigabit… using the same cable (from the same box/roll) as the one I’m using between the faulty computer and the network…

Final post:

Weeeeird… for some obscure reason, everything just went back to “normal” and is all up to 1gb… without touching anything… lol! will have to monitor…