PostgreSQL Database connection issue on RDS with dblink

I've two databases on the RDS instance. Let's say db1 and db2. I'm trying to do a query like this with dblink on db2.

SELECT * FROM dblink ( 'dbname=db1 port=5432 host=<host_ip> user=<user> password=<password>', 'select count(*) from my_table' );

And getting errors like this:

ERROR:  could not establish connection
DETAIL:  could not connect to server: Connection timed out
    Is the server running on host "<host_ip>" (IP) and accepting
    TCP/IP connections on port 5432?