This section describes how to change the database port of an RDS primary instance or read replica. If you change the database port of a primary instance, the standby instance's port will also be changed.
If specific security group rules have been configured for a DB instance, you need to change the inbound rules of the security group to which the DB instance belongs after changing the database port.
in the upper left corner and select a region and a project.
in the upper left corner of the page and choose Database > Relational Database Service.
first and then click the target read replica name.RDS for PostgreSQL instances can use database ports 2100 to 9500.