Constantly getting disconnected

I’m constantly being disconnected.
Tried restarting my router, and clearing all cache files, which didn’t help so far.
What else can I do?

If you are Customer of Deutsche Telekom Ag you could look in the following Thread.
Using a VPN can help in some cases.

I have also had this issue for months. Checked router settings and made sure none of the network settings on my Mac mini would interfere. Strangely I only seem to have the issue when jumping into a different system and it’s always intermittent.