To assist with this can you get the following outputs from the broken system:
# Change 'hostname.local' to the hostname expected to work cat /etc/nsswitch.conf systemctl status avahi-daemon journalctl -u avahi-daemon --boot avahi-resolve-host-name hostname.local getent hosts hostname.local ** Changed in: avahi (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1952496 Title: ubuntu 20.04 LTS network problem To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/avahi/+bug/1952496/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs