RouterNAT

Free networking tool

CGNAT Checker

Compare your router WAN address with your public IP to identify likely CGNAT or upstream NAT.

Check this connection

Your public IP and the WAN comparison form will appear only after you request them.

RouterNAT does not save the displayed or submitted IP address in its application database.

How this CGNAT check works

Your router receives a WAN address from an upstream network. RouterNAT compares that address with the public address visible to this server. An address inside 100.64.0.0/10 strongly indicates carrier-grade NAT.

Important limitations

A mismatch alone cannot prove CGNAT. VPNs, proxies, multi-WAN connections, IPv6, mobile data, and stale router information can change the visible address. Confirmation from your ISP may still be required.

Privacy

RouterNAT does not save submitted WAN IP addresses in its application database. Standard server access logs may record connection information for security and operations.

Learn more

Read the complete CGNAT detection guide