🔶 Unexpected Routing Behaviour in AWS with VPC Peering and NAT Gateway

When routing VPC peering traffic through an internal NAT gateway in AWS, response traffic bypasses route tables via connection tracking, making all subnets in the peered VPC reachable even without return routes configured. AWS confirmed this is "expected behaviour.".

https://labs.reversec.com/posts/2026/03/unexpected-routing-behaviour-in-aws-with-vpc-peering-and-nat-gateway

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