Error 521 Web Server Is Down

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This article will talk about Error 521 Web Server Is Down. But first, it is important to say that there are special services to monitor the online status of a site and assess site accessibility.

One of these services is the BAILRY service – a free regular (periodic) website accessibility check. This service also has a paid subscription for constant monitoring of site availability.

Error 521 occurs when the web server drops the connection to CloudFlare.

This can happen in two cases:

  • the server is not responding or is unavailable. It is necessary to check the functionality of the server;
  • the web server is blocking CloudFlare requests. Since CloudFlare operates as a reverse proxy, all requests to the servers come from CloudFlare IP addresses. Sometimes the hosting security system mistakes persistent connections from the same IP addresses for a DDoS attack. As a result, CloudFlare IP addresses are subject to blocking/rate restrictions.

How to resolve error 521 Web Server Is Down

The web server may be down or working intermittently. In this case:

  1. Make sure your web server is running properly.
  2. Review the server error logs to determine the cause of the error.

If your web server or hosting provider is blocking Cloudflare requests, whitelist all of the service’s IP address ranges in your server firewall or other security software.

Finally, it is important to note that the trust of clients and users in your website, as well as your position in search engines, directly depend on the availability of your resource (website) at any given time.

And you can control this availability using the BAILRY service – a unique software product that has no analogues on the market. To stay informed, sign up for a free regular (periodic) website accessibility check today!