I have been working on this issue for the past two weeks now and I am completely stumped. After running a network scan, half of my devices show the error "Connection to RPC server in the workstation failed". Even after following the steps to disable the firewall (removed from DC and workstations) and applying the scan_setup.vbs (running manually AND as a user logon script), I am having this error returned to me when trying to rescan my workstations. If there is any relation, a few of the workstations failing to scan aren't even grabbing the host name - all that is listed is an IP address. I am using version 8.1.0 build 8110