Hi @TTOBY . You set up a port forwarding rule in the router which directs external port 44158 to the local computer running the application, which will normally be using the same port number.
The computer should have a reserved local ip address so the rule always finds the computer.
When the app is running, do netstat -an command on the computer. Check that port is listening.
You can use a port scanning tool on the internet to check the connection.
Consider using DDNS to track your dynamic WAN ip address.
Port forwarding won't work if you use 4G/5G wireless broadband because of CG-NAT.