Site to Site VPN issue

Can you describe your setup in detail? In the meantime, here is a troubleshooting guide for a VPN with AWS.

The most common issues I come across with vpn is

1. The security group does not allow traffic form the remote IP address
2. The route for the remote network has not been added to the VPN configuration.
3. Route propagation is not enabled across the route tables associated with the subnets where the resources reside.

Network connectivity is always a 2 part problem.

Network path - is there a route from where you're initiating the connection to the destination? You may want to check your route tables at the subnet level, transit gateway level (if applicable) and if you're connecting from on-premises: local router route tables. Think of this as whether there's a paved road between the two systems.

Firewalls - they're everywhere... think of these as checkpoints where your packets "stop and show their papers..." your packets either pass through or get dropped. Some things to check:

• does your destination security group permit the incoming connection? does your source have an SG? does it permit the outgoing connections to the destination?
• does either operating system built-in firewall allow both outgoing connections to the destination and does the OS on the destination permit incoming connections?
• do you have a custom NACL assigned to your subnets (from where the connection originates and the destination subnet)? If so, rules must be defined in both directions...
• if you're connecting from on-premises, is there a firewall that requires a rule to allow you to connect to the cloud resource?

It's also possible that the copy may need some configuration within the app in order function, like binding the web server to a new IP...