strange behaviour with RDP clients connecting to Windows 10 machines

[Gary Dale]

I recently had the unpleasant experience of "upgrading" a pair of 
Windows 7/Pro computers to Windows 10/Pro - the 9 month old version, not 
the latest install image. That's when I discovered the Windows 10 
"feature" that it doesn't allow VNC connections when the monitor is 
turned off (or not attached).

I enabled Remote Desktop services on both machines and can connect to 
them when the monitor is off using RDP. However, even though I installed 
the same version of Windows 10/Pro on each, they behave differently. One 
was a long drawn out slug fest to get the "upgrade" to work (it still is 
having problems with roaming profiles) while the other was a 
straightforward.

I connect using an ssh tunnel to a stretch server with local port 
forwarding so my connection is to localhost:3388. The ssh command 
specifies the machine I want to connect to (e.g. ssh <remote ip> -L 
3388:10.0.0.25:3389). This way I never expose a Windows machine to the 
Internet. The only way in is through the server.

The machine that gave me the trouble on the upgrade connects without 
problem using KDRC but not Remmina or Vinagre. The other computer 
connects without a problem using Vinagre but not KDRC or Remmina.

Remmina gives a message saying "Unable to connect to RDP server 
localhost" when I try connecting to either machine. Vinagre on the first 
machine brings up an authentication dialog then crashes. KDRC does the 
same thing when I try to connect to the second machine.

I'm probably going to "upgrade" both to the latest Windows 10 version in 
the coming weeks, but for now I am puzzled about why I have to use 2 
different programs to connect to 2 machines that are largely identical.