I can't access 'http://acme-v02.api.letsencrypt.org:443/' from my Cpanel/WHM server. It shows me 'Connection refused.' It seems my server IP is blocked by Let's Encrypt!
It is a Cpanel/WHM server with 200 websites that worked well until 2 days ago!
No, it's not. The IP address your server is resolving for acme-v02.api.letsencrypt.org is not a correct IP address for our API endpoint. What DNS resolver is your server using?
Something is very wrong. Your server's DNS resolver is returning that IP address for acme-v02.api.letsencrypt.org incorrectly, and somehow also returning an incorrect reverse DNS lookup for that IP (there is no reverse DNS for it, let alone 000webhost.com). I'll leave this thread for others to help with further troubleshooting.
I found the problem. Your point was very helpful. We set up an application on our server for DNS management. I have since removed it, and I can now access your server. It was a DNS misconfiguration on our server.
I'm glad you resolved your DNS problem. Just for future reference you must use HTTPS for that end point. Attempts at using just HTTP like you tried will fail. Your curl should be like this