Can't access the Db instance on RDS using pgAdmin

I created a DB instance on RDS with easy create following Create DB instance section, then I tried to connect to it using pgAdmin according to what is mentioned in Connecting to a DB Instance Running the PostgreSQL Database Engine section.

When I create the sever on PgAdmin I got this error:

Unable to connect to server:

Could not connect to server: Connection timed out (0x0000274C/10060)
Is the server running on host "xxxxxxxxxxxx" (xxx.xxx.xxx.xxx) and accepting TCP/IP connections on port 5432?

I checked the Troubleshooting Connections to Your PostgreSQL Instance in the documentation but I configured everything well.

The Db instance configuration is mentioned below:

I found a similar question PGAdmin III cannot connect AWS RDS and the answers mentioned didn't fix my problem.

Does anyone have an idea how to fix that?

Your screenshot shows that the inbound traffic to the the DB is only allowed from security group (SG) sg-1fe9297e. The is the same SG as the DB instance is using.

Thus you need to ensure that the instances where pgAdmin is running also use the same SG and are in the same VPC.

However, if you are trying to connect from the outside of the AWS, you need to modify the SG to allow internet traffic. Preferably limited to your work/home IP address/range.