Hi there!

From the notes, I understand that you launched the Debian 11 instance type i3.large, which failed the instance status check. While you managed to launch the Debian 11 with instance type t3a and Debian 9 with i3.large successfully.

The instance status check failure indicates an issue with the reachability of the instance, which can be caused to fail by the following:

• Failed system status checks
• Incorrect networking or startup configuration
• Exhausted memory
• Corrupted file system
• Incompatible kernel

When an instance status check fails, you can address the problem by rebooting the instance or by making instance configuration changes. Please refer to [1] on how to troubleshoot instances with failed status checks.

Although the instance status check fail could be caused by multiple factors, please note that if you use a custom AMI from the AWS Marketplace, there is a possibility that the AMI selected does not support, or is not configured to use the instance type.

I hope you find the above information helpful.

Have a great day ahead!

References:

[1] https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/TroubleshootingInstances.html