Cloudflare error 521: web server is down
Cloudflare reached your origin's address, but the web server refused the connection: nothing is listening, or a firewall blocks Cloudflare.
Where it failed: the origin behind Cloudflare
What visitors see
Cloudflare's "Web server is down" page with a Ray ID.
Usual causes
- The web server (nginx, Apache, IIS) is stopped.
- A firewall, security plugin or host blocks Cloudflare's IP ranges.
- The origin listens on another port than the one Cloudflare uses (443 for Full SSL).
How to tell which one it is
- From your own network, connect to the origin IP on port 443 or 80: refused means the server is down or the port is wrong.
- If it works from your network but not through Cloudflare, Cloudflare's addresses are blocked.
What to do
- Start the web server and make sure it starts on boot.
- Allow Cloudflare's IP ranges (cloudflare.com/ips) in the firewall and in security plugins.
- Check the SSL/TLS mode matches the ports the origin listens on (Full and Full (strict) need port 443).
Check the site now
The Down Checker names the layer that failed (DNS, connection, TLS or the server) and decodes the error page it gets.
Free, no sign-up. Scan only sites you own or may test. 60 scans an hour per address.