Want to share my Fix.
Two days ago upgraded my WD PR2100 and lost connnection on one of the computers on network (windows 10 connected on a Windows SBS I think 2011).
After a 1-2hrs with Tech Support and getting Level 2 tech who access computer. Could not get me to connect and told me it was an issue I would have to call Microsoft support (which I did not do).
Anyways I played with the settings and the following worked
changed the following gave me access (allowed me to map from that Windows 10 computer on a domain)
Settings>Network>Windows Services>SMB Protocol>SMB 2, SMB 3
Settings>Network>Windows Services>NT Lan Manager>NtLMv1 and NtLMv2
The Os5 upgrade changed the NT Lan Manager setting on me.