session data depending on 'www.' in URL

Hi


Retrieving session data doesn't work properly anymore with me since Firefox, Vs. 39.0 (not in Chrome or Safari). The problem: I set session data over the URL 'www.mydomain.ch/login'. If I want to retrieve those session data over the address 'mydomain.ch/mycontroller' (without www.) I got redirected to the login page (meaning: no session data found).

This is annoying since some people use the website with 'www.' others without.

By the way: I have rewriting url already established in .htaccess (however without effect)

RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

Had anyone similar problems? How can I get around this? Should I make a sort of front-controller that redirects all 'domain.ch/controller' to 'www.domain.ch/controller'?

Thanks Martin