I ran into this issue the other day with a new HPE StoreOnce deployment. When attempting to connect to a CIFS share on a StoreOnce appliance (it does matter if it is physical appliance or VSA) from a Windows 2012 R2 server, the following error is received “The account is not authorized to log in from this station”.

To fix this, navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters and set RequireSecuritySignature = 0  and then reboot Windows.  When Windows comes back up, you should now be able to browse the CIFS share on the StoreOnce appliance.