Slow Internet on 1 PC, caused by OS global autotuning level????  

Was working on my son's PC last night and it said there was a new GeForce driver. I downloaded it, and it seemed like it was downloading slow, but I chalked it up to internet bandwidth. A few minutes later, I decided I too should update my PC's Nvidia driver, and on my PC the download was very fast. 60MB/sec give or take, compared to son's 1.2MB/sec.

Went to son's PC and tested Nvidia again and still slow. Tried a few ISO downloads from the web, and his computer seemed stuck at 1.2MB/sec (give or take), where my PC would run 20-30MB/sec using same mirrors.

I rebooted his PC and it was still slow
Tried Brave browser, Chrome and Edge...all slow
Tried changing his network cable, still slow
His mobo has wifi, so I unplugged ethernet and tried wifi and it was still slow
I tried updating his LAN drivers from Asus, still slow
I uninstalled his LAN drivers from ASUS, rebooted and went with standard windows discovered drivers, still slow.


Opened command line as admin, ran this command, but things continued to be slow
netsh int tcp set global autotuninglevel=disabled

Ran Windows update, downloaded the optional cumulative update for Windows 10 1909, and system was still slow.

Went back and re-enabled the autotuninglevel with
netsh int tcp set global autotuninglevel=normal.

Viola....speeds were back. Now, his Nvidia downloads were coming down around 50-60MB/sec via Chrome or Brave. Tested the large ISO downloads and speeds matched my other PC on my network.

So, took a Macrium image and made a note in case I ever saw this again.

Figured I would share here in case anybody here sees something similar.

-Pat

what is the default state for global autotuning??? First time I hear about it. How was it set in your PC?

This is a feature first introduced in Vista that is still present in Windows 10. I didn't tweak or make any changes to my system with respect to these settings. So, these settings were where they would have been out of the box on an install.

My system was set at the normal level when I started, you can check your status with
netsh interface tcp show global