Your website comprised of two tier. Frontend in GCP, and the backend is in AWS. It seems your frontend server is not able to communicate the backend server.
In this quiz, you can assume everything in AWS is setup correctly. Spot the misconfiguration in GCP.
VPC > Firewall
VPC > Routes
VPC > External IP
VPN > Tunnel
VPN > Gateway
terraform configuration file Download
I used Classic VPN with policy-based routing
- - Policy-based ... Specify both local network and remote network
- - from 172.16.0.0/24 and going to 10.0.0.0/24
This is not the communication we are expecting. The frontend server to backend server communication is done "from 10.0.0.0/24 to 172.16.0.0/24".
In order to mitigate this, the vpn tunnel needs to be re-created because this policy cannot be changed on the fly.