Firewall requirements for Jmix deployment?

My application runs fine when tested locally and accessed via localhost:8080
or via the ip address.

However, when I use a domain name that forwards tcp/ip traffic from the external ip on my router and port
8080 to the target server, results are quick failure… a page or two works, then nothing…
I get the feeling that more ports have to be configured for the firewall. any suggestions?

You can see any browser request (requested url and port) in a browser “Web Developer Tools” tab.
F12 or “Control + Alt + I” shortcut.