Before I get bit in the butt again, I am documenting this. Using rdesktop from Linux, I was not able to connect to a Windows 10 client. I found this. This what I did:

Change the registry key
\HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp\SecurityLayer

from DWORD Hex '2' to a value of '1'