Download speed limitation - desktop

Hi,

my desktop seems to be limited to +- 5MB/s if downloading from single source, when downloading from multi source i get full speed of my internet.
Other devices in my home does not suffer from this "phenomena".
Ive tried downloading on my:
phone - i get full internet speed.
notebook - wifi and only ethernet cable - full internet speed / what allows network card

Also checked my router if its not limiting specific device in this case my desktop, but its not - ive contacted even people on forum dedicated to that brand of router "synology" and i have ruled out that it might be issue with router.

I tried to disable FW, uninstalled several unneccesary SW from my desktop and still nothing.
I also tried via windows settings reseting network settings - it required reboot, and still nothing.
Also tried uninstaling LAN drivers and used these two from asus support page for my MB
10.35.510.2019
2019/08/0112.52 MBytes
Realtek LAN Driver
Install Realtek LAN Driver.

10.34.307.2019
2019/07/0312.53 MBytes
Realtek LAN Driver
V10.34.307.2019 for Windows 10 64-bit---(WHQL)

TUF GAMING X570-PLUS (Realtek® L8200A)
windows 64bit pro
winver: 1909 (build 18363.900)

Here are for example tests from same servers - speedtest.net T-mobile Prague server for Multi and Single
and you can see that limitation on these two pictures:




Can anyone think of something that might help?

Thanks a lot,
neyoneit

- - - Updated - - -

I tried Linux on USB and it is working just fine... so its something with Lan driver :/

solution was - completely reinstal windows, this fixed it.
Ive tried everything and i gave up - fresh windows install worked.