@stefanheinemann Thanks for the question. The domain stays in configuring until we’re able to validate that DNS is configured properly and the TLS certificate has been issued. You can check these DNS settings using the terminal or command line app on your computer. The values for nslookup example-app-name-12345.ondigitalocean.app (the generated domain) should match the values for nslookup example.com (the domain you’re trying add). If this is still giving you trouble, please contact DO support (“Contact Support” link at the bottom of the page) so we can look into this.

Thank you for your answer. I’ve come back after the weekend, and the domain is still in “configuring”. I suspect there is a misconfiguration of the DNS setup.

The setup is as follows: assuming example.net, I have a subdomain dev.example.net which has NS entries pointing to the Digital Ocean Nameservers (ns*.digitalocean.com). So everything under dev.example.net is managed by DO (There are already various dropplets running there)
Now I’m trying to add project.dev.example.net in the App configuration which gets stuck in the configuring.

I also tried adding A and NS records to project.dev.example.net in the DO Networking configuration, but it didn’t work.