VNC - Remmina - acces remotely through the internet

I would like to use Remmina for remote access through the internet (from Ubuntu 22.04 to 20.04).

Screen sharing already allowed, what do I enter in the input field "Remmina VNC plugin - Basic - server"? Somehow all attempts have failed such "213.34.33.111:5900", etc. What is the correct format? And do I need port forwarding in my router? How do I set up my router (port forwarding). I already know my local machine's local IP address (192.168.1....). Access from within my LAN worked already, but this is not what I require.

Thanks.