Your port forwarding configuration looks ok. The next step is to find out your external IP. Your router’s configuration page should show this (it’s also known as WAN IP). Or you can open a browser on any device that’s connected to your WiFi, and google “what’s my ip”. That shows your external IP as well.
When you are on cell network, you can use
externalip:8080
to access the controller (obviously externalip is whatever your external IP is).