How to use this tool
- Open your router's Internet or WAN status page and copy its address. The router's LAN login address is a different field.
- Enter a public result captured at the same time, or use the current public-IP button. Check that both addresses use the same IP version.
- Read the explanation and follow the suggested router or provider checks. The result is a clue, not an automatic diagnosis.
Carrier-shared space and private WAN addresses
An IPv4 WAN address in 100.64.0.0 through 100.127.255.255 belongs to the shared carrier range. This often accompanies CGNAT, where a provider translates several subscribers' traffic to public addresses. Confirm your provider's actual service rather than relying on a range match alone.
A private WAN address can occur when your own router sits behind another router, or when the provider supplies a private address upstream. The first case is often called double NAT. The helper distinguishes those clues but cannot inspect the equipment between your router and the internet.
A mismatch has several possible explanations
A VPN or proxy can change the address a website sees. A router may also have several WAN connections, or the public address may change between checks. With IPv6, your router and device may each have their own globally routable address, so different addresses do not imply NAT.
Matching same-family addresses gives no indication of upstream translation for that request. It still does not establish that inbound ports are reachable: router firewalls, device firewalls and provider filtering are separate checks.
What should I ask my provider?
Ask whether your package includes a public IPv4 address, whether it uses CGNAT and whether inbound connections are supported. If you need remote access, describe that requirement. Ask about supported IPv6 or public-address options and any cost before changing the service.
The helper compares only the values you enter. It does not log into the router, scan ports, bypass restrictions or change settings. Your WAN input stays in browser memory; the optional public-IP button makes an ordinary request to this website.