CGNAT and double NAT assistant
Port not opening? Compare your connection addresses before changing router settings. This assistant identifies clues; it cannot determine the cause of an unresponsive port on its own.
Your WAN IPv4 is analyzed only in this browser. It is not sent, saved or added to the URL. Public IP detection uses your normal connection to this site.
How to interpret the result
CGNAT shares public addresses among subscribers. Double NAT can involve two routers in sequence. This tool compares information you provide; it does not access router administration or attempt to open ports.
VPNs, proxies, multiple uplinks, DS-Lite and IPv4/IPv6 differences can affect interpretation. Matching addresses do not guarantee open ports; a timeout does not prove CGNAT.