I feel like this is a weird question that might not even be an issue with my Tailscale setup but here goes. We have 2 RDS databases, a primary and a replica. The primary is not publicly accessible and is access controlled via security groups within our VPC. The replica is publicly available and that is controlled via IP restrictions in a security group. They are both in the same VPC but on different subnets. The private subnet that the primary is in has a route table with a local and a NAT gateway entry. The public subnet that the replica is in has a local and an internet gateway entry.
I’ve set up tailscale with a subnet router according to the docs. I can access the private primary RDS instance but I cannot access the read only replica. The connection times out as if it can’t resolve the host name or as if a security group is preventing access. I’ve triple checked everything (CAVEAT: I’m a networking neophyte) and the only difference I can see is the NAT Gateway versus internet gateway in the route tables.
My main question is just to confirm that I should be able to set up access via tailscale to the replica in the public subnet. I don’t see why it should matter whether it’s publicly accessible or not.
I’d welcome any tips for debugging why connections timeout to the replica.