Can't add another site as a subdomain for an existing one

I have a working site that is managed by Netlify ( and now I’m trying to add another one as a subdomain ( Can’t figure out which DNS records to add (CNAME/ALIAS are giving me dns_api 503 in the DNS record add form).

And the Domain management settings section shows “Awaiting external DNS”:

There’s a Netlify DNS zone for this domain, but no DNS records associated with it. Please contact support for setting up DNS records.

This appears to be resolved. Do you still need help?

Indeed, it seems to be resolved (no changes on my side)