What Should I Do If an ECS Cannot Connect to an RDS for PostgreSQL Instance Through a Private Network?

Perform the following steps to identify the problem:

1. Check whether the ECS and RDS for PostgreSQL instance are located in the same VPC.
   • If they are in the same VPC, go to 2.
   • If they are in different VPCs, create an ECS in the VPC in which the RDS for PostgreSQL instance is located.

2. Check whether the security group rules of the RDS instance are appropriate.

   For details, see Configuring a Security Group Rule.

3. On the ECS, check whether the RDS for PostgreSQL instance port can be connected.

   The default port of RDS for PostgreSQL is 5432.

   curl -kv EIP:5432

   • If the ECS can connect to the DB instance, no further action is required.
   • If the ECS cannot connect to the DB instance, contact technical support.