Problems with my DNS were preventing me to do stuff on my homelab. So I switched DynDNS from inwx.com to desec.io. Much, much better, faster and easier to set up. Awesome! Also, the CNAME entries work much faster than with INWX. But maybe the things with INWX just need to spread a bit longer.
@carsten@yarn.zn80.net Another good option to bear in mind is the DomainConnect protocol, depending where you buy your domains: https://www.domainconnect.org/
It supports basically an open standard protocol of updating your DNS from a local script, and they provide both a Python script and a .NET app to do it.