Problems connecting to CAELinux AMIs

Good evening to everyone

I'm new to the forum and I started using salome-meca few months ago for my graduation thesis
I'm asking for help because I have troubles trying to connect to CAELinux AMIs on Amazon EC2.

I can connect only via SSH to the oldest AMI (CAELinux2010), but not via NX client.
I tried all other CAELinux AMIs but I receive the message "connection timeout" when connecting via SSH.
I followed the instructions found on this site, and I read the troubleshooting documentation in AWS but I couldn't fix the issue.

Thank you in advance for any help
Regards

Francesco