As the cifs mounter is dumb (sorry Linux friends - Windows is decades ahead in many aspects) you might have to tell the SMB protocol version because your NAS might have been stripped to allow SMB 1.0 .. and just -t cifs would try SMB 1.0 only.
As the cifs mounter is dumb (sorry Linux friends - Windows is decades ahead in many aspects) you might have to tell the SMB protocol version because your NAS might have been stripped to allow SMB 1.0 .. and just -t cifs would try SMB 1.0 only.