Allow Propagation Seconds > 600 for slow DNS providers (e.g. netcup needs 900–1800s) #4958
Description
Some DNS providers (notably netcup) have very long DNS propagation times for TXT records used in DNS-01 challenges.
Projects like certbot-dns-netcup and Traefik have documented that netcup DNS zones are only reloaded roughly every 10 minutes, and in some cases propagation can take up to 20 minutes, so values of ≥900s (and practically often 1200–1800s) are recommended.
In Nginx Proxy Manager’s new React-based certificates UI, the Propagation Seconds input has a hardcoded maximum of 600.
This makes it impossible to configure a propagation delay that matches netcup’s behaviour. As a result, Let’s Encrypt DNS-01 validation with the built-in netcup plugin tends to fail on the first attempt, and sometimes repeatedly, simply because the TXT record is not visible yet.
The back end / certbot plugin itself can handle higher propagation values; the limitation seems to exist only in the front end.
Pls increase the hard limit to something like 7200 (2 hours) to cover all realistic cases.