Unable to access my Apple TV 4K with error message

When I try to access our Apple TV 4K we receive the following message: "Apple TV app isn't available right now. Check your internet connection and try again."

I tried reconnecting, connected via hard-wire, restarted router, etc. Nothing seems to resolve the issue.

This is a relatively new device.

[Re-Titled by Moderator]

Original Title: Apple TV 4K Will Not Connect