I have a multisite with parked subdomains. The IPs on the parked domains are all set to point to the admin/main site, the DNS likewise. Two subdomains were set up last year seem to work fine. Adding two more now fail returning the error ‘Missing or invalid site address’.
The wp-config seems to be correctly set for domains and the URL seems to be correct in phpmyadmin. Disabling plugins has no effect, restoring from backup has no effect, but I haven’t been using the site for some weeks. I am the only admin. The webhost support looked into it but can’t see the problem and tell me it’s not server related (ie not their problem).