[NextcloudPi] Problems mounting CIFS in FSTAB

Hi …
I am using NextCloudPi with the Berryboot image. I have had real problems to mount my CIFS Drives in the CLI
sudo mount -t cifs -o user=XXX,domain=something // /mnt/files

causes Host down, but ping was ok and nmap listet the ip and domain as available.
I found this page …

and sudo mount -t cifs -o vers=3.0,user=XXX,domain=something // /mnt/files was working for me.

Now I have the same problem in FSTAB
// /mnt/files cifs username=XXX,password=XXXX,uid=1000,gid=1000,sec=ntlmssp,nodev,nosuid,noexec 0 0
causes an error 32, trying mount -a gives the well known Host down.
vers=3.0 doesn’t work
Any suggestions?