AWS RDS for PostgreSQL cannot be connected after several hours

Finally, I found the answer for my problem. For the error of "connection timeout", one of the reasons can be from the security settings. Although I set it as public when creating the RDS instance, the instance is attached with a private VPC security group which is not exposed public. We can attach the RDS instance with a public security group inside the VPC (I don't think it is a good setting, just for the beginner in AWS like me) as below:

• from Services, select EC2, select Security Groups in the left panel.
• click "Create Security Group" button.
• in the dialog, enter the name for the Group, e.g "postgres-public-access"
• in the dialog, click "Add Rule" button.
• In the "Type" column, select "PostgreSQL" or other types of RDS instances (or you can input the port of your RDS instance, usually it is 5432 for Postgres).
• In the "Source" column, enter "0.0.0.0/0".
• Click "Save" button.
• from Services, select RDS, select the RDS instance, click "Modify" button.
• In "Network & Security", "Security group", select the VPC Security Group you just created, in my case, it is "postgres-public-access".
• Click "Continue" button. Now you can go ahead and connect with your database everywhere.

I had to add/edit a rule to the VPC to allow connections from All sources.

Steps:

1. Go to DB > Connectivity & security > click on VPC(vpc-

2. Under Security > Security Groups > open sg-[something] for which VPC ID matches the DB VPC

3. Inbound Rules > Edit Rules > Change Source to anywhere

So it seems that even when creating the DB and selecting allow public access, it only includes the traffic from withing the VPC. By doing the above steps you can allow access to all sources.

I just followed the guide: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_ConnectToPostgreSQLInstance.html

Run through the typical things:

• Make sure the Database is Public! Check in the AWS Website Console, if its Private make it public.

• Check you have the Firewall port open for the software and the port you're trying to connect through.

• When you create a dB in RDS a Security Group is created automatically with the Rule All, All:

• You can add a rule for TCP Port 5432, like I have above.

• Check Username/Password - sometimes incorrect ones get cached.

• Try to ping the dB to see if its a internet connection problem.

I faced the same issue and it end up because of the VPN am using, when i disconnected the VPN i apply to connect.

Select DB -> Modify -> Connectivity-> Save