I keep getting these errors throughout the day and not sure what the problem is and how to correct it. I would be grateful to anyone who can assist me.
Error 521 occurs when the origin web server refuses connections from Cloudflare. Security solutions at your origin may block legitimate connections from certain Cloudflare IP addresses.
The two most common causes of 521 errors are:
Offlined origin web server application
Blocked Cloudflare requests.
See attached image from the emails I receive.