AWS EKS EC2 instance outbound connection issue

If you have already checked the security groups and network ACLs and verified that the configuration is the same for all three EC2 instances, then there may be other factors that could be causing the issue.

Here are some additional troubleshooting steps you can try:

1. Check the routing table of the VPC: Verify that the routing table for the VPC is correctly configured and all the subnets have the same route. You can check the routing table in the Amazon VPC console.

2. Check the DNS settings: Make sure that the DNS settings for the EC2 instances are configured correctly. You can check the DNS configuration in the EC2 console or by logging into the instance and running the command "cat /etc/resolv.conf".

3. Check the NACL rules: Verify that the Network ACL rules are correctly configured and allow outbound traffic from all the subnets.

4. Check the logs: Check the logs of the EC2 instances and the EKS cluster to see if there are any error messages or issues related to network connectivity.

5. Check the instance metadata: Verify that the instance metadata is correctly configured and that the instance has access to the correct IAM role and security credentials.

If you have tried these steps and still cannot resolve the issue, you may need to reach out to AWS support for further assistance.