EC2 wordpress is not loading

The "504 Gateway Timeout" error indicates that the server, in this case, your EC2 instance, is not responding in a timely manner, which can be due to several reasons. Here's a troubleshoot guide for those cases:

1. Assess the Current Status:

Check the EC2 console for any alerts or notifications about instance health or AWS service disruptions. Verify that the instance status checks are passing. If not, this suggests issues with the infrastructure underlying the instance. If the status checks are failing, use the EC2 actions to perform a Stop and then a Start (not a reboot, as that keeps the instance on the same underlying hardware).

2. Instance and Network Troubleshooting:

Attempt to SSH into the EC2 instance again. If you're unable to connect, verify: The security group rules are correct and allow SSH traffic (port 22). The network ACL is properly configured to allow inbound and outbound traffic for SSH. The instance’s elastic IP address (if any) didn’t change or get disassociated. There are no route table or internet gateway configurations affecting connectivity.

3. Review Logs and Services:

If you're able to SSH into the instance: Check the server logs (e.g., /var/log/syslog, /var/log/messages, or /var/log/cloud-init-output.log) for any signs of issues. Check the application logs, such as Apache or Nginx error logs (/var/log/apache2/error.log for Apache or /var/log/nginx/error.log for Nginx), to see if there are specific application errors. Ensure that the web server (Apache/Nginx) and PHP-FPM (if used) are running. Try restarting them if necessary. Verify that the server isn’t out of resources (RAM, CPU). Use commands like top, htop, or free -m.

4. Database Connectivity:

Verify that the database service (e.g., MySQL/MariaDB) is running and accessible. Ensure the web application’s database credentials are correct and that the database hasn’t reached connection limits.

5. Review Changes and Roll Back if Necessary:

Consider any recent changes you made to the server's configuration, themes, or plugins, that might be impacting the service. If a change caused the issue, try to roll back to the previous state using backups or version control systems if available.

6. Address Potential Storage Issues:

Check if the EC2 instance has run out of storage. Full disk space can cause service failures and a read-only filesystem. Clean up or expand the storage if necessary.

7. AWS Specific Considerations:

Utilize AWS CloudWatch to check metrics and set up alarms for high CPU, memory usage, or disk read/write issues. Review AWS Personal Health Dashboard for issues specific to your account and services.

8. Recovery and Backup:

If all else fails, consider restoring from a recent backup of the instance or the WordPress site. Going forward, ensure that you regularly backup your WordPress site and EC2 instance.

9. Contact AWS Support:

If the issue persists, and you are not able to troubleshoot further, contacting AWS support could provide insight into underlying platform issues or give you specific guidance on your instance’s problem.

As you proceed with these steps, document your findings and changes made during the troubleshooting process, which will be helpful for future reference and possibly assisting AWS Support if you need to contact them.

This also seems a duplicate of: https://repost.aws/questions/QUwzIxbpCKR7ejtoqeBRm0CA/wordpress-website-is-not-working and https://repost.aws/questions/QUclRWZHmkT3GQAlc8s7BtnQ/website-and-wordpress-not-loading

Let me know if you found your fix so others can benefit from this.