Error: The processing of Group Policy failed because of lack of network connectivity to a DC. This may be a transient condition. A success message would be generated once the machine gets connected

This error is self-explanatory, as it states: The processing of Group Policy failed because of a lack of network connectivity to a domain controller.

This was because the Domain Controller was not available, as shown below.

I can now apply Group Policy Network Connectivity Error correction correctly after turning on the DC.