USB Apache: check local and Internet ports

Use Network & ports in USB Apache to test the configured port. A local TCP check works offline. Check from Internet needs Internet access and the fred.my port-check service.

• Start Apache first and check that its port matches the port you are testing.
• If the local check works but the Internet check fails, review LAN/WAN mode, Windows Firewall, router forwarding and CGNAT.
• If the service is unavailable, retry later; unavailable does not mean the port is closed.
• Wait at least ten seconds between Internet checks. The service tests only the public IPv4 address of the caller, not an arbitrary target.

What an open result means

An open result proves a TCP connection can be made to that address and port. It does not identify the application answering there.