Also thanks for this advice, this seems easier than I thought.

Thanks for the pointer, I will try that…as soon as I have repaired the network stuff that I somehow broke 15 minutes after I wrote the last text by trying to upgrade the host-debian system the webserver VM lives in.

But yes, its a problem with other devices, but actually not with the windows gaming pc that is connected via cable, only Wifi devices seem to have that problem. I actually checked if the swap to the guest wifi (because for some reason it has better connection?) and it doesnt, so its at least not that