I'm getting Error 521 but disabling cloudflare solves the problem

[bailey.stringer]

Hi there,

That is weird if you have allowlisted the IPs and Cloudflare not being able to communicate with your server. There is a guide on this error that I will link here;

Community Tip - Fixing Error 521: Web server is down

Error Try the suggestions in this Community Tip to help you fix Error 521: Web server is down. Background A 521 error happens when we are unable to make a TCP connection to your origin server. Specifically, Cloudflare tried to connect to your origin server on port 80 or 443, but received a connection refused error. This is often caused by security or firewall software and happens if the origin server has directly refused Cloudflare’s proxy request. [Banner in tip catalog] Quick Fix Ideas …

However it is most likely an issue with Cloudflare communicating with your origin.