I am trying to generate certificates from lets encrypt for kong. I am using acme plugin for the same and i am following ACME | Kong Docs
Everything is working as expected but when i try the step
curl https://example.com -k (putting in my actual domain name)
The response i am getting is
<html>
<head><title>521 Origin Down</title></head>
<body bgcolor="white">
<center><h1>521 Origin Down</h1></center>
<hr><center>cloudflare-nginx</center>
</body>
</html>
what could be wrong.
Additional Information: I am using an AWS ec2 instance for kong server and port 443, 8000, 80, 8001 is open.
Also, i have already created an A record for the domain in cloudflare.