Why am I having trouble connecting to my EC2 instances?

There are several potential reasons why you might be experiencing trouble connecting to your EC2 instance and encountering status check issues. Let's address these issues and discuss ways to prevent them:

1. Instance Status: First, ensure that your instance is in the 'running' state and has passed its status checks. You can verify this in the Amazon EC2 console under the "Instances" section.

2. Status Check Failures: EC2 performs two types of status checks - system status checks and instance status checks. System status checks monitor AWS systems, while instance status checks monitor the individual instance's software and network configuration. Failed status checks can be due to various reasons, including:

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

3. Resource Utilization: Your code running in the background might be consuming excessive resources, leading to instability. Monitor your instance's CPU, memory, and disk usage to ensure it's not overloaded.

4. EC2 Instance Connect: If you're using EC2 Instance Connect, verify that you have the necessary IAM permissions and that the instance has EC2 Instance Connect installed.

5. Security Groups: Check that your security group rules allow inbound SSH traffic from your IP address.

To prevent these issues and improve stability:

1. Use CloudWatch Alarms: Set up CloudWatch alarms to monitor status checks and instance metrics. This can alert you to problems before they cause downtime.

2. Auto-recovery: Configure automatic recovery for your instance. This will automatically recover the instance if it becomes impaired due to underlying hardware issues.

3. Regular Maintenance: Perform regular updates and maintenance on your instance to ensure it's running the latest software and security patches.

4. Resource Optimization: Review your code and optimize it for better resource utilization. Consider using a larger instance type if your current one is consistently under high load.

5. Use Amazon EC2 Auto Scaling: Implement Auto Scaling to automatically replace unhealthy instances and maintain application availability.

By implementing these measures, you can improve the stability of your EC2 instance and reduce connection issues. If problems persist, you may want to use the AWSSupport-TroubleshootEC2InstanceConnect runbook to diagnose specific connection issues related to EC2 Instance Connect.
Sources
Troubleshoot issues connecting to your Amazon EC2 Linux instance - Amazon Elastic Compute Cloud
Connect to an Amazon EC2 instance using EC2 Instance Connect Endpoint - Amazon Elastic Compute Cloud
Status checks for Amazon EC2 instances - Amazon Elastic Compute Cloud
Resolve EC2 Instance Connect issues in EC2 Linux | AWS re:Post