How to connect multiple ssl certificates for virtual subdomains?

Question

Digital certificates

Kind!
On the VPS, spin a site that has a main domain, like example.ru and, about 15 subdomains - city.example.ru
One move and a script is used that defines $_SERVER["HTTP_HOST"], substituting all variables in the future. Thus, we get 15 regional sites and one main site.
ServerName example.ru
ServerAlias ​​*.example.ru
...
I'm thinking about how to connect to all, or at least to the main ssl domain
, WoSign now allows you to register no more than 3 or 5 subdomains, and browsers don't like it either.
WildCard - too expensive
As I understand it, such an implementation is not feasible, because first there is a connection, and then the domain is determined. Or am I wrong?
Is it possible to tie ssl only to the main domain example.ru without affecting subdomains?

Answer 1

Give subdomains with URLs like example.com/subdomain1/, then one certificate will be enough, or buy a wildcard certificate, or (I recommend this option) get yourself certificates from Let`s Encrypt, each of which allows you to add up to a hundred names.