smb v1
might be a cooincidence, but just had a call where an old nas box disconnected for no reason. turns out to be because it uses smb v1, and since yesterday, it hasnt worked. fix is to enable smb v1 in windows components (and also possibly check for ms client in network adaptor, turn off ipv6 and enable netbios over tcpip).
probably caused by recent win 10 patch