@juergenbrandstaetter said in How to configure Dynamic DNS with unsupported DNS provider:
In my case I my providers router works in bridge mode, and my WAN interface is configured as DHCP -> so I guess it should recognize, if the IP changes
Not recognize
If you use a DHCP client on your WAN interface, this client will initiate a DHCP lease request as soon as the WAN interface comes 'UP'.
The ISP, with it's DHCP server, will give the client an IP (your WAN IP), a gateway, maybe a DNS or two.
A DHCP lease has always a duration, like 24 hours. So, half way that duration, the DHCP client will wake up, and request for an DHCP lease 'extension'. It will of course suggest that it likes to keep the actual (WAN) IP.
The ISP DHCP server can grant that lease extension, or so, "NO, now you get a new IP (WAN)".
The WAN IP changes (or not) a "interface event" is fired, and this will affect all processes that are "bound to" these interfaces, so that these process can be made aware that an IP on some interface changed (or not).
On of these process is : the DynDNS. It has stored the (now past) WAN IP in a file, it will compare it with the actual WAN IP, and fire up a dyndns update if the tow are different. And it will update the file with the current WAN IP for future events.