Xcode Cloud to GitLab - Connection Error -"Your hostname must be publicly resolvable."

We are trying to implement Xcode Cloud for CI. We have a private repository in GitLab that can be accessed via VPN. We are experiencing the following errors while connecting Xcode Cloud to GitLab. We followed the steps provided by Apple.

Connection Error to https://git------.com. Your hostname must be publicly resolvable.

How can I resolve this issue?

Thanks