Question about firewall and server

Hello everyone I have the free version of Cloudflare for my website and recently I started getting error 520 (very rarely), someone told me that I should add my server to the Cloudflare firewall.
Here are the options I see:



He told me that in the Cloudflare firewall I should put the IP of my server in bypass and with all the options (the 5 that I see and that I understand are free). Is this correct? In operator should I put equals?

Any help?

This won’t do anything if you’re saying users visiting your site are getting a 520 error.

They probably mean that the firewall on your server or hosting provider should be allowing all of the IP addresses listed in cloudflare.com/ips/