How to make friends Drupal 7 running on IIS with virtual directories?

Question

Drupal

The task is the following, there is a web server (virtualka on IIS) on which sites are spinning, it is necessary that the file part be stored on a separate web server
. ideally, in the Drupal settings in the file system, specify the path such that all site files (i.e. sites / default / files) are poured onto the file server
Tried to create a virtual directory in which I specified the path from whom to log in when entering the folder, and it seems to have created a folder, but drupal does not smell it as a folder / link, and when changing settings in the file system, it simply creates a new folder that I specified in the settings, but does not pay attention to the virtual one