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This can be done by a computer, smartphone, or any gear that can enter the internet.
HTTP is a protocol or rules that govern the exchange of information over the internet.
Such information on the status of a request made to a server is communicated using status codes.
Status codes have different classes, which are identified by the first digit in the status code.
One such status code is 521, which means the Web Server is Down.
This is an unofficial status code used by CloudFlares reverseproxy service.
Such an architecture ensures that no client directly communicates with a web server with the resources it is requesting.
An example of CloudFlares reverse proxy services is its Content Delivery connection(CDN).
ACDNconsists of geographically distributed servers that cache web content close to the physical location of users.
This results in faster loading speeds of content on the internet.
This in turn, results in Error 521.
When this happens, it leads to Error 521 even though the origin server might be working fine.
#3.Origin Server Misconfiguration
Cloudflares Content Delivery data pipe(CDN) is a reverse proxy service.
Servers need to be properly configured for them to work with a CDN.
Firewalls being configured to drop packets instead of refusing connections also leads to Error 521.
SSL Certificates are used to authenticate the identity of websites and establish an encrypted connection.
How to Fix Error 521
There are a number of ways to solve Error 521.
However, the second tested server was down at the time of writing.
Zero packets were received from it, and it had 100%packet loss.
Additionally, ensure that your firewall is configured correctly to avoid it dropping packets.
This leads to Error 521. the requests can make.
If youre running your own dedicated server, ensure that your firewall is not blocking Cloudflares IP addresses.
These Cloudflare encryption modes are useful in establishing a connection between Cloudflares reverse proxy service and the origin server.
Full or Strict modes are the most popular choices or encryption modes used as they require an SSL Certificate.
When using these modes, Cloudflare requires valid SSL certificates from the origin server.
To overcome this, installCloudflare origin certificatesto your origin server or use SSL certificates from a trusted certificate authority.
When using Cloudflare, you might encounter Error 521, which could indicate a problem with the origin server.
In such a case, consider the solutions given above.
In case all of them fail, consider getting in touch with Cloudflares customer service for further assistance.
