Client migrating to new server, Winsows 2019 with Sage 300 2020.  Existing server is Windows server 2008, running Sage 300 2016.

On the old existing server, Sage uses Windows authentication for many users.

On the new server, when I try to change the user from Sage300 login to Both, and select the user from the domain list, when I save, i get an error "Invalid windows user"

What have I missed to allow this to happen on the new server?

Sam