CloudFlare 521 Error on properly configured server?

Question

cloudflare

To begin with, I will say that the server is most likely configured correctly. Why? There are two more domains on the server from different registrars (reg.ru, reg.ti), which are also linked via cloudflare. Access to them works both via http and https.
Why, then, is another domain from the registrar beget.com giving an error 521? This is the problem. A couple of days ago I installed cloudflar's dns's in the beget'a panel (i.e. the fact that dns has not been updated yet - we brush aside immediately). Also, the domain is available via http and leads exactly to the desired server (specified through the A record in cloudflare)
Question: what's wrong then? The domain itself: siliconhbo.ru
An interesting fact: when you add a "test" record to the same ip, the new subdomain is not accessible either via http or https protocol.
In beget'a support they say that they are not involved in this in any way.
What could be the problem?

Answer 1

Maybe you just haven't changed ns on your computer. I advise you to check your site under vpn