I’ve asked the same question already but have not recevied any answer other than “the origin disconnects”.
We are experiencing 520 error. It happens few times per hour. We checked everything we could, we have also changed our server for the new one with more performance. We have excluded the possibility that our server is responsible for that as we tried to reach it directly (without cloudflare) and no 5xx error was registered. We also generated huge number of requests directly to our server and did not experience any 5xx error.
When we connect via Cloudflare we got the 520 for a few times per hour.
None of Cloudflare IPs is blocked on firewall. Our VPS provider does not block anything. Our server is loaded for 20% of its performance most of the time. But 520 still happens.
The last time we experienced the 520 the Ray ID on request was 633937219a432c76.
How to resolve this issue?!