EC2 instances cannot connect over Elastic IPs

Question

I have 2 EC2 instances and I am trying to get them to connect over port 44874 (it's a layer 1 cryptocurrency like dogecoind).

• Both are running Ubuntu 22.04 AMI
• Both are in the same subnet
• Both are in the same VPC
• Security Group:
  • 0.0.0.0/0 incoming on port 44874 is open
  • 0.0.0.0/0 and ::/0 outbound are open on all ports
• sudo ufw status is showing "Inactive" for both
• On my personal computer, I can SSH into both of them from their elastic IPs (22 is open in the SG on my IP)

I am trying to get them to connect with their respective Elastic IP addresses. They will not talk to each other, but they will talk to my wallet when I hit their elastic IPs from my personal computer.

Does anyone know what the problem might be? I have about 10 other servers in this VPC and they seem to all be doing this as well. No problems talking to the outside world, but they cannot talk to each other with their elastic IPs.

Any ideas?

Answer 1

To troubleshoot your network configuration, consider utilizing the VPC reachability analyzer, a tool provided by AWS. This tool helps analyze reachability and visibility within your VPC. You can find more information about it here -https://aws.amazon.com/blogs/aws/new-vpc-insights-analyzes-reachability-and-visibility-in-vpcs/.

The potential issues might stem from incorrect ACL rules or misconfigured routing tables. It's advisable to carefully review and verify these configurations to ensure proper communication between your EC2 instances.