The only thing missing from #1527 is the ability to create a new station and desktop once the system proxy has authenticated the user. We can already launch a shadow server for the user chosen from the proxy system service. (tested when the user is already logged in, works beautifully)
None of the solutions in the links work, at best I get error 1800, I believe this means Your computer could not connect to another console session on the remote computer because you already have a console session in progress but this user is definitely not logged in, via RDP or via the Logon screen.
And I can use the rdesktop command from another computer to connect with the same credentials.
The only missing piece of the puzzle for full support on mswindows. Raising.
(#2750 may help with testing this)
Can be tested with an evaluation version of windows server?
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/2756