This assumes you have set up the Vino VNC server correctly, but the VNC client you’re using gives you a message like “encryption not supported” or “the authentication method requested is not availaible”.

The cause of this message is that the Vino VNC server tries to use encryption with your connection, but most viewers do not support this. To disable it, use the following command: gsettings set org.gnome.Vino require-encryption false or open dconf-editor if you have it, the set org.gnome.Vino require-encryption to false.