The speed test could not run - Error 521

Hey there Cloudflare community!
Cloudflare System Status says “All Systems Operational”, but when I go in Speed Panel I get “The speed test could not run - Error 521” (plz see attached screenshot). The website is visibile at and at , and is hosted on Aruba double hosting, Windows + Linux, but is not visibile at This is a mistake and I can’t solve it. Aruba says that his server is ok for Cloudflare CDN. Maybe I wrong the DNS setting.
Thanks for help!

Hi @log9,

It looks OK to me. Do you have any firewall rules configured that could be blocking this?

If not, I would suggest you contact support.

To contact Cloudflare Customer Support, login & go to and select get more help. Please give Support the complete details and link to your Community post.

Thanks domjh!
I haven’t firewall rules configured. I will try to contact CF Support.

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