What process does the client go through to work out the connection to the server?

Hi, we have this working in a LAN, works well… we would like to put some outside the firewall… so how would this work? How do the internet clients find the server?

Ive read over the ports section but doesn’t really explain the process.

There is a server URL setting to which the client connects. So e.g. urbackup://example.com (using port 55415) or via websocket wss://example.com.