Can't access Time Machine folder from M1 Mac Mini with macOS 12.2.1

Hi community,

just my finished my first install of OMV6.

For some reason I can't access my shared time machine folder from the Time Machine menu in System Preferences. I keep getting the "

Time Machine can’t connect to the backup disk. There was an error authenticating with the provided username or password.

" error. The weird thing is that I am able to access the same folder from finder with the same username. I tried several times (and made sure I was tiping the password correctly) but no luck in backing up my mac data. The time machine option is enabled for the OMV share. Nas' disks are formatted in ext4 and joined in a pool with union fs.

Anyone else encountered the same issue in the past?

Update: turns out I am not even able to access the shared folders. I get the following error:

The operation can’t be completed because the original item for “disk” can’t be found.

I am able to see the smb server, log into it but can't modify or access the shared folders.

Follows my share configuration:

what am I doing wrong?