Is this application serving port 80? Is it connecting to another server on port 80, or is it expecting a client to connect to it on port 80? Does it make some connection, and then offer to serve port 80?
If you want some client on the internet to connect to your machine behind a NAT firewall on port 80, you might want port forwarding, not port trigger.
looks like a decent explanation.
Port 80 is a very popular port. If you set port forwarding to accept an incoming port 80 request and forward it to a mcahine on your network, it will receive a lot of malicious traffic, as software probes will try to discover known weaknesses in a variety of servers that are expected to listen on port 80.