Can I check the availability of a site with specific providers?

Question

Network administration

Is there such a service that could show the availability of a site from different providers? There are some hard-to-reproduce, but stable problems with the availability of the site for some providers.

Answer 1

https://ping-admin.ru/free_test/
I checked here.
It turned out to be a strange butt with the disappearance of the site in several cities.
Transferred to another hosting, in another city - appeared in the cities from the previous paragraph, but disappeared in other cities.
As a result, I did this:
the main server in Moscow,
the second server in St. Petersburg. This is a simple nginx reverse proxy to a Moscow server.
in DNS there are two records of type A:
with St. Petersburg
and with Moscow IP-address.
after re-checking, it turned out that everyone was hurt from all cities except for exotic foreign cities that I do not need (because the website is focused on the Russian Federation).

Answer 2

https://pinghttp.com tests using the Internet connection of the people on the site.

Answer 3

sitealert.ru is a free site availability monitoring service.