I am attempting to shadow existing RDP sessions on Windows 2012 R2 without RDS installed on a custom (not standard 3389) rdp port.
This describes how to shadow RDP in windows 2012 R2. However, when I attempt to do this using for example:
mstsc /shadow:(sessionID) /v:(ip):(port) /control
computer name is invalid.
It appears although mstsc /? shows that one can specify port in the /v parameter it, in fact, does not accept that when coupled with the /shadow argument and results in error message "This computer name is invalid"
mstsc v:IP:port without shadow option is successful, however, obviously this does not result in shadowing.
I have set the registry key
HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services Shadow(DWORD) = 1
To allow shadowing with user permission.
I have also allowed multiple sessions per user in group policy which does result in allowing multiple sessions from one username.