Organize the work of some pages of a WordPress site through access to subdomains?

Question

Domain Name System

I have a WordPress site running over HTTPS (SSL).
It is necessary to implement the possibility of some pages of the site through subdomains.
For example, so that a certain nested page available at: https://mysite.ru/catalog/phones/iphone7/ was also accessible at the subdomain address: https://iphone7.mysite.ru
I tried to use: Page As Subdomain Lite - not allows you to select my page, because it is nested (has a parent page)
Naturally, the SSL certificate only works for the main domain, but not for subdomains.

Answer 1

Naturally, the SSL certificate only works for the main domain, but not for subdomains.

It will already be a problem.
For subpages, if you have Apache installed, then the easiest way to do this is through mod_rewrite. You can read it here httpd.apache.org/docs/2.0/misc/rewriteguide.html