HTTP 521/520 Internal Server Error Very Often

[user3322]

Hi everyone,

Why I got error 521/520 for a while but very often. It’s only 1 minute/error.
Even though the cpu usage, memory, etc is normal. There’s no spike.
I’ve tried deactive all plugins but it remains the same.
There’s 3 sites on my hosting, and all using Cloudflare. Seems like, It affect to all sites when the error comes.
1 of my websites: mulaitradingonline.com

Can anyone help or find out what’s the problem?

Thank you!

[Xaq]

Your hosting uses a security solution which is triggered when CF tries to fetch content and blocks CF servers. Ask them for whitelisting CF IPs.