Backup of Debian server client never registers as finished

Hi! This is my first post to this forum. I hope I don’t write anything stupid.
My set up is the following:
Server: QNAP NAS
Clients: #1 Windows 11 PC
#2 Debian server (Debian 12 Bookworm)

I have the server set so that it backs up the clients daily. The windows client functions as expected and I have both file and image backups.
The Debian server, although everything looks fine in the log file, never registers as finished on the Status page in the web-interface of the server. It seems to restart constantly. Let me clarify that: There is a date for the last filebackup on the Status page, but the column “File backup status” says “No backup exist” (or similar, my interface is in Swedish). What could be wrong?