How to properly transfer an SSL certificate to another server?

Question

Digital certificates

I am transferring several sites that are on the nginx server of one web studio with which I collaborated. So I moved the sites, one of them works on https. I moved it to my apache server, downloaded the .key and .crt files. In the domain settings (in the isp manager 5 panel), I specified the paths to them. But at the same time, all sites on the server fall off completely, and the site for which the certificate was intended gives an error err_ssl_protocol_error.
I don't quite understand what I'm doing wrong. The "ssl certificates" menu contains the expiration date, all the details about the publisher, and so on. Perhaps you need to make a csr request correctly, but I don’t understand how it works. The domain is delegated to Yandex, it has a record on my server.

Answer 1

Are the settings still the same? Does the site name match the name in the certificate?