Revolving 521 error

I have sartoolbox.com hosted and been doing fine for months, not a problem. Today mid day I got a down email notification. I check it and it has the Error 521 from cloudflare. Now I haven’t messed with any settings and not even went to the site for about a week.

It is a wordpress site hosted on digital ocean and I am using the strict SSL option in cloudflare. Haven’t changed any settings for months. The server stats are all good, nothing abnormal. Low load and no errors in any of the logs.

Just not sure what else to check or change, I tried moving from full to flexible ssl/tls but that only made it unreachable.

Any suggestions?

Hello,

A 521 error happens when Cloudflare is unable to make a TCP connection to your origin server. Review the suggestions in this Community Tip for Quick Fix Ideas.

Basically, you’ll need to contact your hosting provider for clues. Ask them to allow connections from Cloudflare’s IPs, as those may have been rate-limited.

Also, even though you say you didn’t change anything on your site, sometimes hosting providers apply automatic updates (especially security updates) to WordPress and some plugins. Your wp-config.php may also be set to perform these automatic updates.

While keeping WP and plugins up-to-date is in general a good idea, this may at times cause strange behaviors. WordPress just did a security update in the past few days (to version 5.7.1).

Finally, you may want to search on Forums | WordPress.org to see if others are facing a similar issue.

Oddly enough, I’m not seeing the 521, so it’s quite likely the Rate Limiting issue @floripare mentioned. Cloudflare’s IP addresses are somewhat regional, so someone far away is going to come from a different Cloudflare IP address than your local audience.

And…of course I spoke too soon. I just checked again and got a 521.

As this is Digital Ocean, how did you set up the site? Was it one of their marketplace one-click installations? Or is it configured and managed by a third party configurator? (I may have made that last word up)

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This is one of the marketplace installs and updated to the latest version. I have 6 sites set up like this and all the others doing fine. However, this one has different plugins installed. I do keep all the plugins auto updates enabled and the linux server updated weekly at least.

No error, do the errors occur at random times?

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