Checker

Best-effort CGNAT checker

Compare the WAN IP shown by your router with the public IP visible from the web. The result is informative only, but it can highlight strong signs of upstream NAT.

Best-effort checker

Compare your public IP and router WAN IP

This tool reads the IP address visible to the server, then compares it with the WAN IPv4 you manually enter from your router status page.

Detected public IP

Checking...

If this value is missing or unusual, the final result may be less certain.

Assessment

Enter your router WAN IP

The checker needs the WAN or internet IPv4 shown by your router before it can compare anything useful.

Next steps

Open your router status page and find the WAN, internet, or external IPv4 address.
Enter the WAN IP exactly as shown by the router.
If the router only shows IPv6, treat this check as informational and confirm connectivity with your ISP or router vendor guidance.

Important disclaimer

Browser-based checks are best-effort only. They can suggest CGNAT, but they cannot conclusively prove every ISP policy, network topology, or firewall condition.

1. Find the WAN IP

Open your router status page and look for the internet or WAN IPv4 address.

2. Run the comparison

Enter the WAN IP exactly as shown and compare it with the detected public IP.

3. Verify the result

If the result suggests CGNAT, confirm it with your ISP and check for double NAT at home.

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