There are unattended Debian stable updates, but I doubt that broke it. Maybe something broken at Netcup? I have no idea how to even diagnose this...
I do not exactly know how long it has been broken, but at max a week.
If anyone knows where I could start here, do tell me please. I am using Firewalld, but again - did not change anything recently.
#IPv6 #Sysadmin #Debian