Troubleshooting
Why port forwarding fails
Port forwarding problems are not always caused by the router rule itself. The real issue is often another NAT layer, the wrong WAN IP, or a service that is not reachable from the outside.
CGNAT or another upstream NAT layer
If your router WAN IP is private, shared, or reserved, inbound traffic may stop before it reaches your own router.
Double NAT inside the home
An ISP gateway plus your own router can create two NAT layers locally, even if the ISP gives the gateway a public IPv4 address.
Local firewall or device settings
Even with a good port forward, the target device still has to listen on the port and allow incoming traffic.
Testing from inside the same network
Many routers do not support loopback testing, so an open port can look closed from your own Wi-Fi.
Work from the edge inward
Start by confirming the router WAN IP. Then compare it with your detected public IP. If those values do not line up, you may be looking at ISP-level NAT or another device sitting upstream.
If they do match, the problem is more likely to be the target device, firewall, app configuration, or how the test is being performed.
The fastest starting point is usually the checker, followed by the guide on finding your router WAN IP.
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