The following script allows you to set up an auto-updating DynDNS using the Netcup API.
Note
You do not necessarily need a Fritz!Box. Anything that can call some URL and provide an IP address will work.
Who is this for?
Anyone who is a customer with Netcup GmbH and has a Domain there, and wants to point, e.g., a subdomain of that to their own home router.