I saw few other persons talking about the same issue.
I only have this on Valheim. I can play another game and even download next to that without any issues.

But on Valheim if I go to a dedicated server. At a moment the internet will reboot.

People a guessing it's the crossplay features who has a bug.
I'm on Intel / Nvidia
I think my friends are on AMD / Radeon and don't have the issue too.

Hope you dev will do something at a moment : ) I can't play with them.