Question Upload speed is less than half what it should be on my main computer, but it's fine when I switch to a second system ?

[Xfeng]

I have two windows installed. The main one currently receives a low upload speed in the speed test by Ookla. The upload speed should be around 45Mbps, but on my main system, the speed is only around 10-17Mbps. interestingly the download speed is as same as all other devices and tests on my second system(all around 920Mbps).
Both systems have the exactly same hardware and driver versions using Driver Easy. (I tried to use MSI official drivers, still act the same.)

Does anyone have any ideas to solve the issue?

I have tried:
1. DISM and SFC
2. disable Large Send Offload V2
3. disable the global autotuning level
4. reset the network
5. Uninstall all network drivers and reinstall(tried both Microsoft version and latest version)

The suspected reason is that it might be caused by Cfos, but I have uninstalled it, and still no improvement.

One of the important notes is that I was using the wired connection for the test, when I switched to wifi connection on my main system, the upload speed jumped to around 36-40Mbps, which seems normal to me since the distance from the router.

Here is the speed test result, It is very abnormal when it comes to upload speed, the speed climb gradually while in other device and my second system, the upload speed climb directly to 40+Mbps, not like this.

 

[Ralston18]

Two things:

1) On your main system verify that only one network adapter (either wired or wireless) is enabled. Not both at the same time nor two enabled adapters of any sort enabled at the same time. One network adapter only.

2) "One of the important notes is that I was using the wired connection for the test, when I switched to wifi connection on my main system, the upload speed jumped to around 36-40Mbps"

Try using the network cable from the "fast" system on your main system.

Swap the cables to determine if the slow problem follows the cable.

 

[gggplaya]

Make sure your computer don't have any killer networking hardware on them. If they do, but sure to ensure they are set for maximum bandwidth, then remove all the Killer software.

 

[Xfeng]

Two things:

1) On your main system verify that only one network adapter (either wired or wireless) is enabled. Not both at the same time nor two enabled adapters of any sort enabled at the same time. One network adapter only.

2) "One of the important notes is that I was using the wired connection for the test, when I switched to wifi connection on my main system, the upload speed jumped to around 36-40Mbps"

Try using the network cable from the "fast" system on your main system.

Swap the cables to determine if the slow problem follows the cable.

1. Yes, I deleted all of them. Only one is enabled
2. They all use the same cable. What I mean is that the two systems is on the same computer. I just installed two windows.

Thanks for you reply~

 

[gggplaya]

Did you download the proper drivers from your motherboard manufacturers website? Never rely on Windows default drivers.

 

[Xfeng]

Make sure your computer don't have any killer networking hardware on them. If they do, but sure to ensure they are set for maximum bandwidth, then remove all the Killer software.

I think I don't, I upgraded to Windows 11 on this system today, and it seems to solve the problem, but I need Windows 10. So I am now trying to roll back to see if the problem goes back.

Did you download the proper drivers from your motherboard manufacturers website? Never rely on Windows default drivers

Yes, as I mentioned, I used both official from MSI and the latest, both act the same