521 error page

Hi Community,

I am very confused about why I keep getting this error message.

I just made a video that I think might make your head spin.

I am normally in Costa Rica, and have no issues with my website. Upcoming coming to Greece, I keep getting this 521 error. But none of my tech guys in the US can replicate it or find what is happening in the logs.

And when I used a VPN based in the US, the 521 error did not come back.

I made a video for my web person.

Can anyone help? Does anyone have any ideas what could be going on?



Hi @aaron25,

As you noted from the error page, a 521 usually indicates a problem with the origin server, rather than with Cloudflare. A 521 error happens when Cloudflare is unable to make a TCP connection to your origin server.

This Community Tip has most of the common causes. As you are seeing this error intermittently and from specific locations only, my best guess would be that your server/host is doing some rate-limiting/blocking of some of Cloudflare’s IP ranges. You should make sure that Cloudflare’s IPs are allowed through any protection you have on your server to avoid this.

Thanks for your reply.

Then how do you explain that when I use a VPN through the US, that there are no issues with the website, but as I am using the internet in Greece, Cloudflare is creating this 521 error?

I’m not saying that this is definitely the problem, just a suggestion to look at.

Given that Cloudflare uses different IP ranges in different datacenters to connect to origin servers, it could seem like a local issue if the host is blocking some connections from specific IPs.

I just found this article.

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