I am using VPN as admin to loginand
add his domain logon to the local administrators groupand
add his user to the user and group manager
Not but a cannot because there is nothing to login to. No user added yet.But the user *is* already a domain user, right? On a domain, any domain user can log on to any workstation - in general at least. No prerequisites for doing this except being a domain user, having the workstation joined to the domain and being currently connected to the domain / AD.