Hi @prakhar, we don't think your server is denying CloudFlare requests. If so, you would have added an entry in your AWS firewall/security group or in iptables for such purpose (you can check this with "sudo iptables -L" inside the instance), but it's likely that's not true.
Could you try to enable CloudFlare, and once configured, see if it's reaching Apache? You can see this if the file /opt/bitnami/apache2/logs/access_log gets a new entry when you access the page.
If the entry is added to access_log with CloudFlare enabled, it's possible that there's a misconfiguration in your server causing the failure (e.g. a redirection issue).
Could you check this and let us know?