Why does macOS show ".local" domain name for TimeMachine server when my network is configured for ".lan"
This may be occurring due to accidental usage of Avahi/Bonjour. If you mount the Time Machine volume to your Mac and click 'Get Info' on a file stored on it, you may see something like smb://lunar._smb._tcp.local/Chrono/. This indicates that the server was automatically discovered because it offered an SMB service. If you were connecting via the hostname it would read smb://lunar.local. If this seems accurate, the solution is to either disable Avahi or Bonjour on your server, or to manually mount via the hostname and change your Time Machine disk.