The error message says the hostname is not publicly resolvable. Meaning if you type in the domain name in Safari's address field when you are on the open Internet (not connected to your company's VPN), Safari will report that it could not locate the server.
You mention that you are following the steps given by Apple but did not provide details. So I can only provide a general answer here. Off the top of my head, your setup must have the following:
- Your private GitLab server must not be only accessible via VPN. Xcode
Cloud/Apple will not have VPN access to your company private network.
- The domain name you use must be resolvable on the Internet. Meaning
that there is a publicly accessible DNS that can turn your domain
name to a publicly routable IP Address. Non-publicly routable IP
Address look something like
192.168.x.x
, 10.x.x.x
,
172.(16-31).x.x
.
- Your company network's firewall must allow traffic coming from Apple to
access the server where your GitLab instance is on.