If you receive errors like:
“The connection was ended because of a decryption error on the server.”
“An internal error has occurred.”
from your client, the fix is quite easy.
From the command prompt run the gpedit.msc applet.
Navigate to Computer Configuration / Administrative Templates / Windows Components / Remote Desktop Services / Remote Desktop Session Host / Security
and then disable the “Require user authentication for remote connections by using Network Level Authentication policy”