Real VNC Viewer doesn't have an option to start in listening mode.
To accomplish this, we need to start a Terminal window and use this command:
/Applications/VNC\ Viewer.app/Contents/MacOS/vncviewer -listen
No window or confirmation is shown.
Just use VNC Server's option "Attach to listening vnc viewer" and use the proper address on your Mac.
You may need to add an IP Forwarding rule on your router to allow communication from external port 5500 TCP to insternal port 5500 TCP, if you want this to work from Internet.
