Ubuntu 17.10 & 18.04 – Configure x11vnc to boot at startup – Griffon's IT Library
Ubuntu 14.10 – Configure your sytem to have x11vnc running at startup – Griffon's IT Library
VNC from boot on Ubuntu 10.04 all the way to 14.04 without logging in, using LightDM (or GDM) and x11vnc (includes LUbuntu with lxdm and Linux Mint LMDE with mdm) - Seb
VNC server on Ubuntu 20.04 Focal Fossa Linux - Linux Tutorials - Learn Linux Configuration
Ubuntu 17.04 – Configure X11VNC Server to Boot at Startup – Griffon's IT Library
How to Setup X11VNC Server on Ubuntu & LinuxMint – TecAdmin
Kousik Chatterjee's Blog: How To Install & Configure x11vnc Server on Ubuntu 14.04