DNS ERROR or address not found

Hello.
Several months ago I had this problem, I already migrated from hosting, I changed the person responsible for registering the domain, I used clouflare and I stopped using it, but nothing works.
The problem is that on some devices the site appears as “unreachable” or with a DNS ERROR. This happens on cell phones and PC, at the same time other users see the site without problems.
On my cell phone (last generation) I see the site in chrome but in firefox and in another browser I get that the web does not exist to check the url (but it is fine) or sometimes the DNS ERROR.
I have had this problem since last December, and it seems to come and go, because a month ago I was viewing the site in all browsers and today I have the aforementioned problem.

On the other hand, I have users who visit the site, send a contact form, I send them a link to another part of the site and they answer that they cannot see the site, that the DNS ERROR appears when it was 5 minutes ago they could see it.

The hosting says that everything is fine on its side and it cannot reproduce the error.
On my PC using google DNS I see the site without problem. But a few months ago it happened to me to be able to see it in chrome but not in firefox.

Another curious fact is that I have other sites on the same hosting, and I can see them well in all browsers, where the other site is not visible.

Anyone have an idea what it can be?
The site is: https://n9.cl/jwtqx

Here is another screenshot from another browser.