Hi all, I have same problem with this. Im using cpanel and this plugin doesn’t work. When i pointed my browser to https://sub.domain.com, it always redirected to https://domain.com. But thanks to Shumaher You inspired me. Yes here is what i have done.
First, upload Domain Mirror plugin and activate it.(download it here) then go to Domain Mirror’s options page to configure it in settings page. add your new subdomain there and save changes. Next, go to your CPANEL subdomains page and add subdomain there, make sure your Document Root pointed to your WP installation directory, in my case it is /public_html. Last step is edit your Category Description to your subdomain and make sure this category has atleast 1 article. That’s it.
sorry for my bad English ??