Why
Operators use CGNAT to deal with the lack of IPv4 addresses. Several customers then go out on the Internet with the same public IP, while the operator manages an additional translation.
Aftermath
Home hosting, inbound port forwarding, and some peer-to-peer games or services become difficult, if not impossible, without a dedicated option. The problem is not your local router, but the translation layer at the operator.
How to identify it
Compare the WAN IP displayed by your router with the public IP displayed by VoirMonIP. A WAN address in 100.64.0.0/10 is a strong index of CGNAT.
Possible solutions
Some operators offer a full stack IPv4 option or a fixed IP. IPv6 can also solve many inbound uses if the service and firewall are well configured.
Frequently asked questions
Is CGNAT dangerous?
Not in itself. Above all, it changes the incoming reachability and network diagnostics.
Can I open a port behind CGNAT?
Not effectively without an option operator, tunnel or other architecture.
Reference sources
To be explored next
Published and verified by the VoirMonIP.com team on July 15, 2026.