I have determined that the reason for that string literal is because of the network configuration on our side. It since has been changed and the message did go away in place of an error 503 (Service unavaliable)
netstat doesn’t show anything on port 443 (it does however show something for port 80). I think this is the underlying issue there.
As for DNS it is discoverable - the actual address that is used is from an already registered domain, but with the additional redirection to gitlab (so any additional redirections need and are done on our side)