EX2 Ultra rarely makes backups

I recently bought an EX2 Ultra. My intetion was to use it for hourly backups with Time Machine. After a few weeks it stopped doing backups hourly. Now most of the backups fail. A sign turns up that I can’t interpret. Should I return my EX2 Ultra to the store? Or is there a quickfix? I tried to understand how to upgrade it but I failed.

Every time Time Machine fails to do the backup this error message comes up:

Kunde inte komma åt avbilden ”/Volumes/.timemachine/Marvin._smb._tcp.local./F0D93161-D84D-4F13-A8D2-19DCA001C88C/TimeMachineBackup/Hubbelina.backupbundle” som används för säkerhetskopiering (fel 45).

It say something like “couldn’t reach the icon/image…that is used to create the backup (error 45)”

I’m on MacOS Catalina.

Hope for advice!