Bad connectionquality and packetloss after windows clean installation

Hi, so yesterday i did a clean windows reinstallation on pc.
Installed all the drivers etc. Downloaded the latest version of TS3.
Logged in with my acc and got all my settings back.
Then after i joined our server that we are using for around 4 years a realized that my connection quality dropped slowly from 86 to 25-30% and i also got a packet loss (20-25%). Beside that like one out of 5 connections doesnt work the first time and i got an error. Same thing when quitting the server. It tells me that i lose connection rathet then disconnecting me.
Imgur: The magic of the Internet → image

Its just on our server. My connection on other TS3 servers are stable at 94% without packetloss.
All of my friends have perfectly working connection.
I didnt change any hardware, settings in TS3 or my router configuration.
My internet is fine.

What i tried:
reinstalled TS3 serveral times
tried to to join the server without login as guest
i even reinstalled Windows again

Hello this comes either from your computer or from the server but not from the client we would have a lot more complaints if the client was not functioning properly regarding your problem

Sincerely

I agree with you but i´m looking for help analysing the problem. Any tips?

vérificateur tes pilote ici https://www.driverscloud.com/

you make me laugh to report this which is a world famous site to check if driver