Question Only one PC on splitter has low speed ?


May 23, 2015
I recently bought a TP-Link mini ethernet switch, there are a total of three computers connected to it and another ethernet cable connected to a router. Two of three computers get our full gigabit down, but mine is capped at around 550mb down? I'm wondering what the issue could be, I know it's something to do with my computer just not sure where to start. Not the splitter because I tried my computer in different ports and into the router even, but to no avail.
First check with another Ethernet cable to rule out the cable.
If all is the same then check adapter settings.
Network and internet
Change adapter options
Right click your Ethernet connection
At top "Configure"
Advanced tab
Speed and duplex.
First try "AUTO negotiation"
Or you could set it to 1gig full duplex if your adapter is a gigabit adapter.
If it does the same thing plugged directly into the router then you are correct it has to be something with the pc.

This tends to be software on the pc limiting it. If you have a 2.5g port some of the older drivers had a lot of issues make sure you are using one from the chipset vendor and not some microsoft generic one.

There are 2 other very common causes. The first is a older feature called autotuning. Generally you want this option on but I have seen some discussion of turning it off but that should make things worse in theory.

netsh interface tcp show global

The autotuning should be "normal"

The other common one that causes this are so called "gamer" network software. These claim to give you lower latency etc etc. This is mostly a lie since it can not affect traffic outside your machine and if you have a overloaded network interface inside your machine you have a far worse issue.
This software come bundled with video cards and motherboard, asus tends to be the worst offender. The most common name is called CFOSspeed but asus sometime calls it "lanfirst". You want to uninstall anything that claims to favor certain type of traffic or provide QoS for traffic.

You can try a very simplest test between 2 machines connected to the switch not call it a splitter it confuses some people... There is a older line mode program called IPERF. You should be able to transfer data between 2 machines in your house at over 900mbps both in and out. It pretty much only tests the interface and the drivers and any network equipment in the path. It is very simplistic so it is not affected by say disk speed or memory and since it does not use things like a web browser it eliminates most more advanced software as the issue.