All activities stop several times a week

All activities stop several times a week. After rebooting the server everything works again. We’ve been looking for the cause for weeks but can’t find it.

UrBackup server version 2.5.27
Different UrBackup client versions (~ 42 clients)
Almalinux 8.7
We only use file backup. No Image backup

The problems already existed before we updated to version 2.5.27.

Last time all activities stopped is 2023-01-14 20:13.

Part of urbackup.log-20230115:

2023-01-14 20:08:11: ERROR: Sending broadcast failed!
2023-01-14 20:08:11: ERROR: Sending broadcast failed! (ipv6)
2023-01-14 20:08:12: Files WAL file urbackup/backup_server_links.db-wal greater than 1000 MB. Doing full WAL checkpoint...
2023-01-14 20:08:13: Full checkpoint of urbackup/backup_server_links.db-wal done.
2023-01-14 20:09:01: ERROR: Sending broadcast failed!
2023-01-14 20:09:01: ERROR: Sending broadcast failed! (ipv6)
2023-01-14 20:09:51: ERROR: Sending broadcast failed!
2023-01-14 20:09:51: ERROR: Sending broadcast failed! (ipv6)
2023-01-14 20:10:41: ERROR: Sending broadcast failed!
2023-01-14 20:10:41: ERROR: Sending broadcast failed! (ipv6)
2023-01-14 20:11:31: ERROR: Sending broadcast failed!
2023-01-14 20:11:31: ERROR: Sending broadcast failed! (ipv6)
2023-01-14 20:12:21: ERROR: Sending broadcast failed!
2023-01-14 20:12:21: ERROR: Sending broadcast failed! (ipv6)
2023-01-14 20:13:11: ERROR: Sending broadcast failed!
2023-01-14 20:13:11: ERROR: Sending broadcast failed! (ipv6)
2023-01-14 20:13:24: Files WAL file urbackup/backup_server_files.db-wal greater than 1000 MB. Doing full WAL checkpoint...

full log sent to bugreports@urbackup.org.

Big file sizes in /var/backup:
1.0G backup_server_files.db-wal
1.1G backup_server_links.db
94G backup_server_files.db
230M backup_server.db
386M clientlist_b_7031.ub
423M clientlist_b_6358.ub
958M fileindex