Struggling to connect to EC2 instance via Fleet Manager

Check that the AMI you specified is supported by Fleet Manager for that instance type. Not all AMIs work on all instance types.

Verify that the IAM role used by the fleet has the necessary permissions for the new instance type. Some instance types require additional permissions.

Make sure the security group allows access to the new instance type. Some instance types may use different ports.

Stop the existing fleet before editing the fleet configuration with the new AMI and instance type. Then start the fleet again.

Review AWS documentation for the latest instance type specifications and AMI guidelines for Fleet Manager. The combination of AMI and instance type may not be supported.

As a test, try launching a single EC2 instance with the new AMI and instance type using the AWS console to see if it comes up successfully. This will validate the AMI and instance type are configured correctly before using with Fleet Manager.

Let me know if stopping the fleet, updating the configuration, and restarting doesn't resolve the issue.