Why is my EC2 Linux instance unreachable and OK its status checks?

Hello.

Have you checked the web server error log or system log when you can no longer access the web page?
Is it possible that the web server is unable to handle it due to some kind of load?

Hello check these steps to resolve issue:.

Check Security Groups and Firewalls:

Ensure your security group has inbound rules allowing traffic on port 80 (HTTP) or 443 (HTTPS), depending on your web server configuration. Double-check that these rules haven't been accidentally restricted. Verify that any firewalls running on the instance itself (e.g., iptables on Linux) are not blocking access.

Web Server Health:

Investigate your web server logs for any errors that might be causing the service to crash or malfunction. Common web server software like Apache or Nginx will have log files that can provide clues. Use the AWS Systems Manager Run Command feature to connect to the instance and check if the web server process is running. If it's not, investigate why it's stopping and ensure it has proper startup configurations.

Instance Health:

Check the instance status in the EC2 console. Look for any system health events or logs that might indicate resource exhaustion or application crashes. Use tools like Amazon CloudWatch to monitor CPU, memory, and disk usage on the instance. Spikes in resource consumption could be causing instability.

1. If you're using an Elastic IP address, ensure it's properly associated with the instance and hasn't been disassociated accidentally.
2. Verify that your DNS records (A record) point to the correct public IP address of the instance.

https://repost.aws/knowledge-center/ec2-instance-hosting-unresponsive-website