Web app connection troubleshooting checklist

Basic:

1. Does your DNS A record point to the correct IP address?
2. Does DNS checker show mostly green marks for your domain and does it show the expected IP address?
3. Does ping <server IP address> get a response?
4. Has at least 4 hours passed since you updated the A record?
5. Does ping <domain name> show the expected IP address and get a response?
6. Is your web server running?
7. Is the web app called by your web server running?

Extra:

1. Check if the correct ports are open and listening.
2. Ensure no firewall rules are blocking access to the web server or specific ports.
3. Review web server logs (e.g., Apache, Nginx) for any unusual entries.
4. Verify that SSL certificates are valid and have not expired.