Why can't ec2 see RDS?

Question

Amazon Web Services

- EC2 and RDS are in the same VPC, (10.10.0.0/16);
- Subnets are different, but they belong to the same VPC (10.10.10.0/24,10.10.11.0/24,);
- Created SG for all IPs (0.0.0.0/0) on port 5432; Outbound everything is allowed around (EC2 and RDS)
- The route to the postgres is built through the trace route, but pings do not go;
- Route table for VPC local created

Please tell me what other reasons could there be?

I check through: nmap [dns name of rds].us-east-2.rds.amazonaws.com -p 5432

Answer 1

the problem is in the very method of checking: nmap does not see either the instance or the open port

Answer 2

Another great person forgot to allow ICMP traffic)