Error 523 with Full (strict) encryption


After adding Cloudflare signed origin certificate to my nginx, I am getting Error 523.
If I change the SSL setting back to flexible, it works fine. If I don’t proxy through Cloudflare, my site works fine, and the certificate from Cloudflare is served (but not accepted by browsers, which is expected).
So nginx is able to use the certificate, its only when connecting from Cloudflare to my server there seems to be an issue.
Any pointers to resolving this issue?


Did you notice any error logs in your server?

No logs. I don’t think the request is reaching my server. The error is

Check your DNS Settings. A 523 error means that Cloudflare could not reach your host web server.

But the IP hasn’t changed, and without full encryption, Cloudflare can resolve the DNS.

So the issue was on my ISP side. They had blocked 443, but not 80. And to have 443 opened, I need to pay additional monthly. Anyways that’s a different topic.

Heh…they want to snoop on your traffic unless you pay them not to. Then again, hosting a website on your home device is always a bit iffy.

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Is it possible to configure such that Cloudflare use a different port when accessing origin server? The end user can reach cloudflare with https (443), then cloudflare forwards an encrypted request to, say, 8443 on the origin server?

Certainly. Someone has a subscription service called Portzilla:

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Thanks! So much cheaper than ISP plan :slight_smile:

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You could also use Cloudflare Tumnels, which are even cheaper.


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