Error 521: Web server is down when origin server is google cloud

Recently I do migration from cpanel to google cloud. Then I set my external IP in cloudflare’s DNS,

  • Without cloudflare proxy, its running good,

  • But when I use cloudflare proxy, it shows Error 521: Web Server is down.
    For overcoming this, I update ufw, as follow:, this script allow cloudflare IP ranges whitelisted.
    But the sad thing is, still I get Error 521: Web Server is down.
    I searched over the google, but still I can’t solve the problem.
    What should I do now?
    My site:

Before you added it to Cloudflare, it was working with HTTPS?

I tried 1 minute ago and it was working.
Just now it seems you’ve got a certificate problem and it’s down (prefere Full encrytion [Encrypts end-to-end, using a self signed certificate on the server] to full strict.

1 Like

No Bro

You saw the lets encrypt ssl. But the problem still not fixed.

I observe that, when i enable universal ssl then my https website shows 521 error and its still not solved.

1 Like

This topic was automatically closed after 30 days. New replies are no longer allowed.