So I have a Xubuntu box, an old PC that was running Windows previously. All is peachy with the Linux install bar one thing: every time I shutdown the system, it shuts down fine, but immediately restarts again. This wasn't happening with Windows and appeared to be an issue particular to Linux or Ubuntu.
Here are the steps I used to get X11VNC working on an Ubuntu (19.10) box. Hope this helps somebody else out there too.