unable to connect to AWS VPC RDS instance (mysql or postgres)
问题 (I'm posting this question after the fact because of the time it took to find the root cause and solution. There's also a good chance other people will run into the same problem) I have an RDS instance (in a VPC) that I'm trying to connect to from an application running on a classic EC2 instance, connected via ClassicLink. Security groups and DNS aren't an issue. I am able to establish socket connections to the RDS instance, but cannot connect with CLI tools (psql, mysql, etc.) or DB GUI