GCP Cloud VPN will not come up: reading the IKE logs (peer not responding, traffic selectors narrowed) and BGP with pfSense
Logs Explorer with resource.type=vpn_gateway and the IKE status text. ‘peer not responding’ = IKE version, PSK, IP or UDP 500/4500; ’traffic selectors narrowed’ = phase 2 subnets that do not match. With pfSense and BGP: permit route maps in/out or no routes are accepted.