AWS instance connection refused restored db instance

Question

I cannot connect to a restored rds instance. I create a new rds instance by restoring_from_snapshot.

It copies all settings except the security group so I modify it after boot.

Now I cannot get psql to connect to 5432 on the endpoint.

Despite identical settings old working instance (can be access is in live usage)

new test instance based on snapshot

I have the exact same settings on both instances. The new instance starts with the default vpc sec group but I modified it to have the same. The Instance also had many hours trying to propagate dns info. I have been trying the whole day to fix this.

What could I have possibly missed here. The difference between the old(live) and new(test) is that the latter has no Multi AZ, no Backups, no Minor Version Upgrade. Ports are all default postgres 5432

psql response is that it asks for password with the new it says

psql: could not connect to server: Connection refused
    Is the server running on host "**********.eu-central-1.rds.amazonaws.com" (**.**.**.**) and accepting
    TCP/IP connections on port 5432?

Answer 1

看来我们公司的防火墙不会让我进入5432端口。