Cloudfare Host is down error 521

i added ip4 of cloudfare into iptables but still when i go to my website using https i get Error 521 : Web server is down. Please help its urgent

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Site Moderator
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March 8, 2021
Accepted Answer

Hello there,

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.

You can also make sure that port 443 is open with this command:

  1. iptables -A INPUT -p tcp -m tcp --dport 443 -j ACCEPT

Also, you can check our tutorial for whitelisting IPs with iptables:

Regards, Alex