Redirecting homepage to subdomain

[COOLak]

I chose the subdomain approach for my site, which resulted in having to use custom routing. But then the "homepageRedirect" is not working properly. I set use_accept_language_header to true and added the following code to my routing:

 homepageredir:
    path:               /
    defaults:           { _controller: 'controller.frontend:homepageRedirect'}

It redirects homepage to mydomain.com/locale, while I need it to be redirected to locale.mydomain.com
Any suggestions? Thanks in advance.

[COOLak]

Was able to solve this via .htaccess, but still wondering how to do this via this extention.