I’m pretty confident in your case (I’m not sure I understand user7472’s so much at this point) your issue is not related to Cloudflare at all. I can cURL your origin (as we have demonstrated) from my local machine, and your origin resets the TCP connection. It’s hard to overstate how fundamentally bad that is for your website being available on any platform. Your host really needs to fix that for you - it has nothing to do with Cloudflare or any other company, other than the host themselves.
🎉 $ curl -svo /dev/null http://example.com --connect-to ::184.108.40.206 * Connecting to hostname: 220.127.116.11 * Trying 18.104.22.168... * TCP_NODELAY set * Connected to 22.214.171.124 (126.96.36.199) port 80 (#0) > GET / HTTP/1.1 > Host: example.com > User-Agent: curl/7.64.1 > Accept: */* > * Recv failure: Connection reset by peer * Closing connection 0