Implementing Vary:User-Agent

MageStack natively supports the Vary: User-Agent header, however, as it isn't a setting applicable to all stores, it is disabled by default.

To enable the User-Agent vary header, you only need to set a single variable in your vhosts configuration,

Edit your ___general/ (where is your chosen domain), and add

set $magestack_vary_user_agent true;

Then restart Nginx via Monit.