If a domain is offline, the service tries at regular intervals to reestablish connectivity. If the domain has been offline for more than one hour, the service can't establish connectivity. You can reconcile the domain to manually reestablish a connection between the domain and the cloud.
If the domain is offline because you shut down the domain, start the domain before you reconcile the domain status. If you just initiated a domain restart, wait for the domain to start before you reconcile the status.