Cloudflare DDNS behind NAT

[simonalexanderjones-60]

Hi, I'm looking for a solution to update Cloudflare DNS records when my CGNAT IP changes. My UDR7 is behind NAT which means it has a local IP address. My ISP router doesn't support bridge mode. I was hoping to use this project's Cloudflare worker to solve the problem. Does anyone know if it will work when running behind NAT? My concern is that the local IP address assigned to my UDR never changes (unlike my CGNAT public IP) so will the Custom DDNS setup ever get triggered? Maybe it's timer triggered rather than triggered on an IP change? Can anyone confirm?

[willswire]

Yes, this worker works behind NAT/CGNAT! Use ip=auto instead of ip=%i in your server URL:

<worker>.workers.dev/update?ip=auto&hostname=%h

When ip=auto is used, the worker reads your public IP from Cloudflare's CF-Connecting-IP header — it doesn't matter what local IP your UDR7 has. UniFi checks DDNS on a timer (~every 2 minutes), so it will fire regardless of whether your local IP changes.

We've expanded the FAQ to cover this — see FAQ #11 in docs/faq.md.