UCS 5.0-5 Update error (host is unresolvable)

Hey guys, I’m having trouble updating to UCS 5.0-5 from 5.0-4.
On the first try there wasn’t enough space available in the /var/cache/apt folder. Resolved that issue.
On the second and so on try the complete installation ran fine and the packages updated but at the end I get the message:
“The connection to the repository server failed: Configuration error: host is unresolvable. Please check the repository configuration and the network connection.”
I have a current working snapshot where I can ping all the repositories but as soon as I run the update it doesn’t work.

Background info:

  • Server runs in QEMU VM on a cloud provider
  • Additionally Tailscale is installed
  • Update is run over a direct console to the QEMU VM

Thanks for all your help!