OpenMarine

I loved Real VNC Server, because with the help of realVNCs cloud feature I could connect through a GSM connection from home.

I know I can deinstall X11vnc and install realVNC again, but, as I am working headless I fear to loose the connection.

Is there a save way to change back to realVNC?

You do not have to uninstall x11vnc, they can coexist. If you do not want to use RDP you can re-install realvnc:

sudo apt-get update
sudo apt-get install realvnc-vnc-server