Why does hairpin NAT testing fail from inside my home?
Some routers do not support NAT loopback, so the public hostname works externally but not internally. Test from mobile data and consider split DNS.
Internal/external test; router loopback; DNS.
Network/security engineering.
Show the technical detail
On a managed Wi-Fi plan
Use supported split-DNS/DDNS design only.
On another provider's router
Router behaviour varies.
What to be careful of
Do not expose service to test it.
Where this comes from: Official · see the original source ↗ · Draft—technical review · checked 17 August 2026