Connection stopped after login

[gtsolid]

Hi,
I configured UVNC server on my WS2012 and the viewer on my W10 PC.
I successfully reach it using a DynamicDNS and 5900 port.
When I'm asked to login by windows (not by VNC, I can proceed after this step), I enter credentials, press enter and then the program crashes.

Do you have any explanation? I lowered the quality to 256 color to have a faster response