Compute Engine automatically provisions new projects with a firewall rule that allows RDP traffic. If you have an existing project, or have modified the configurations, the default firewall rule that permits RDP might not exist. Confirm that a rule allows RDP traffic to connect to the network that your affected instance is on.
To check if the default-allow-rdp firewall rule exists on your project, check the Firewall rules page, or run the following gcloud SDK command:
gcloud compute firewall-rules list
To create a new rule if one does not exist, create a rule with the following command:
gcloud compute firewall-rules create allow-rdp --allow tcp:[PORT_NUMBER]