Question Gigabit LAN only giving 120mbps

[Captain Magenta]

I'm in UK, and have a Virgin Media Superhub 3 on the 200mbps package. It's not possible to change WAN ip on the Superhub for god knows what reason, which is why I prefer modem mode which let's you go dynamic.

Direct connection to PC gives me 220mbps in speed tests, so the motherboard ethernet is fine and can handle that speed. However when I switch to modem mode using a TP-LINK TL-WR2543ND router (which has 4x1 gigabit ports) my speed won't go over 120mbps. Windows show that it's on a 1.0Gbps connection, so it's set correctly but it simply won't go over 120.

Cable wise I have a cat5/cat5e/cat6a. All of them give the full speed when the superhub is in router mode and connected directly.

Any suggestions?

 

[bill001g]

I would reset the router to factory default and then configure only the admin and wifi passwords.

Many feature on router will limit your speed.

That router is 7 or 8 years old. It is so old there are few test results to be found. It could very well be that the router does not have a hardware NAT assist feature and you are being limited by the CPU clock speed in the router.

Modern router have a feature that lets the NAT traffic bypass the main cpu function. Still if you use certain feature this function is disabled and even the fastest routers will bottleneck at about 250mbps.

 

[Captain Magenta]

I would reset the router to factory default and then configure only the admin and wifi passwords.

Many feature on router will limit your speed.

That router is 7 or 8 years old. It is so old there are few test results to be found. It could very well be that the router does not have a hardware NAT assist feature and you are being limited by the CPU clock speed in the router.

Modern router have a feature that lets the NAT traffic bypass the main cpu function. Still if you use certain feature this function is disabled and even the fastest routers will bottleneck at about 250mbps.

I have already tried several resets without luck. I might be getting somewhere though, according to this link https://openwrt.org/toh/tp-link/tl-wr2543nd flashing it with openwrt firmware fixes the WAN to LAN throughput. They report very similar problems to mine, citing the firmware as the issue.

 

[bill001g]

Might be better but most third party firmware has little to no support of hardware assist. Not sure if you router is new enough to have that feature but it could be optimized better for cpu processed NAT.

This is one of the key reasons I stopped using third party firmware after I upgraded my internet.

You can get a $50 router that will easily keep up and I think your router is not actually dual band, if I remember correctly it was one of those routers that only has a single radio chip and you must pick the band it runs on.