Domain not using correct document root

I have three dedicated servers all running Hestia, and one just one of them on a single domain (out of 23 that happen to be on that server), when you go to the website it just shows the default ‘Success’ page, and not the index page that is in the document root. In fact, it won’t show any documents, so (for example), if I create a page /test.htm, then go to that address, I get a 404 error. So I don’t think the web domain is pointing to the correct directory. What’s more, if I go into Hestia settings for the website and select Custom Document Root, change it to specify it’s own root (or any of the other sites for that matter), it still only ever shows the default ‘Success’ page.

It’s a default instal of Hestia (installed as 1.3.2, but auto-updated to 1.3.3) on Ubuntu 18.04 (x86_64). I have LetsEncrypt enabled, which appears to be working and Cloudflare. I tried disabling CF but that made no difference.

Any suggestions as to where I should be looking for the cause of this problem? Things to try to troubleshoot it?

Many thanks in advance for any pointers.

What you are describing happens when a user request for a domain, lets say example.com, reaches the IP of the Hestia server, but the Hestia server does not have a domain with that name (on that IP). The only reason I can think of, is that you have multiple IP addresses on the Hestia server and the domain example.com is listening on a different IP than the one the user request comes through.

If you have multiple ip’s installed make sure you use the correct ip adress.

Only a single IP on the server, so maybe something else?

Is it a recently added domain?

Nope. Been on the server for about 60 days.