Today I was chasing down a bug where a database that was in a peered VPC couldn’t be connected to. It was a good reminder of the things that should be checked when trying to debug networking issues in AWS.
- Security groups (in my case the problem was the SG on the database though I checked that after everything else)
- NACLs
- Route tables
- Make sure you can resolve DNS between the paired VPCs
AWS advice on the matter at the time of writting it mentions everything I do minus security groups