I have a good working installation, well almost, as I have some virtual server with ssl enabled and working certificates on them, some virtual server with no ssl not enabled and obviously no certificate installed.
What works : going to any https virtual server is ok (correct and valid certificate)
BUT if I go to a non enabled https virtual server, I expect it to fail with no connection to the 443 port, but instead it serves the home page with a certificate from the working ones, which fails hopefully (wrong domain).
One solution would be to buy and install ssl certificates for every domain, but I would love another solution…
There is no reason to buy it. You can add up to 100 alternative names (AN) to a certificate, using SSL Certificate page and its Domain names listed here textbox:
if I go to a non enabled https virtual server, I expect it to fail with no connection to the 443 port, but instead it serves the home page with a certificate from the working ones,
This is all correct and this is how Apache works. What you could do, is to create a default virtual host for your server, and then simply put its record at the top of Apache config file or using UI by going to Website Options page and forcing current domain to be Default website for IP address to Yes:
