unable to access CIFS shares from Windows 7 PC's

Model: FAS2240-2

Mode: 8.3.1P2 Cluster-Mode

We have never been able to access CIFS shares on Windows 7 PC's since installation. We can access CIFS share from Windows 10, but now Windows 7.

We receive the message - 'Windows cannot access \\*cifs share name*'

Tried permissions as everyone and defined individual groups, no difference. Users cannot even access the root \\*cifs share name*

Any ideas?