Hi, could you send us the full set of logs from the Windows 11 server ?
%ALLUSERSPROFILE%\NoMachine\nxserver\nxserver.exe --debug --enable all
in a cmd console run as administrator
Reproduce the problem (connect from your Ubuntu client).
Then gather the logs.
%ALLUSERSPROFILE%\NoMachine\nxserver\nxserver.exe --debug --collect
The log archive is created in
%PROGRAMDATA%/NoMachine/var/log/archives
Full instructions are available here: https://kb.nomachine.com/DT07S00243.
Send them to forum[at]nomachine[dot]com. Please use the title of this topic as the subject of your email. Thanks!