OpenNX is an OSS drop-in replacement for Nomachine's nxclient.
I'm using Windows 10 x64 and trying to connect to Ubuntu 16 with XRDP. The port is open and I could partially connect with another XN client, so I guess the port configuration is OK on the server side. The latest version (0.16.0.729) crashed just after I configured the connection and tried to connect, and previous (0.16.0.725) returned the following error: "Unexpected termination of nxssh" In both instances the OpenNX client was running with admin rights and the session was configured to use Unix and GNOME. 0.16.0.729 crashed nearly instantly, but at least it created more detailed log files. When I tried to run the command line which OpenNX used with nxssh it returned no error, but timed out in 60 seconds. When 0.16.0.729 I could run a debugger and it reported that there was an AccessViolation in OpenNX.exe at 0x0089CFCC.