I was able to start up x11vnc by disabling Wayland in the /etc/gdm3/custom.conf file and rebooting as per this post: https://askubuntu.com/questions/981313/x11vnc-on-ubuntu-17-10-not-running-on-startup. I'm not sure what I lose by changing the DM, but for now it seems to be OK.
I was able to start up x11vnc by disabling Wayland in the /etc/gdm3/ custom. conf file and rebooting as per this post: https:/ /askubuntu. com/questions/ 981313/ x11vnc- on-ubuntu- 17-10-not- running- on-startup. I'm not sure what I lose by changing the DM, but for now it seems to be OK.