When connecting to the FWD Application Server via the browser (using a FWD Web Client), then there are two ports in use: the port to access the FWD login page (for non-embedded clients) and the port on which the FWD Client's embedded web server will start (for all clients), after launching the associated FWD Client JVM.
If the browser accessing the web client and the associated Web Client JVM are on the same network (or on the same machine), then here is typically nothing to do to enable connectivity. However, if this is done from separate systems, then the firewall on the client must be configured to properly support the port(s) in use.
The FWD Web Client will rely on a websocket connection between the Browser and the embedded web server running in its associated FWD Client JVM; the communication protocol over this websocket allows passing input from the user (key-presses, mouse events) to the FWD Client and the FWD Client passing drawing primitives (and other commands) to the FWD Web Client. The performance of the FWD Web Client running in the browser will depend on the network latency between the systems where the browser and the actual FWD Web Client JVM are running.