Thank you for your quick reply. I did a
1) clean install of nomachine_4.2.26_1_amd64.deb,
2) and followed the instructions to start Xvfb on display :0 as a non-root user
ps -ef shows:
1002 10252 1 0 18:09 pts/1 00:00:00 Xvfb :0 -auth /home/googlestudent/Xvfb-0.auth -screen 0 1280x1024x24
and netstat -l shows:
tcp 0 0 *:4000 *:* LISTEN
When I try to attach using nxplayer, it actually connects and lets me enter the password for the non-root user, but instead of connecting to the Desktop I get the attached error screen instead (Ooops! Could not start the display server. Error is 5: Input/output error). I will attach the error logs.
When I try this same sequence as the *root* user, then the final connection to a Desktop is successful, but I would like to do this as a non-root user.