If you want your game to communicate with your own host then you'll need to add the appropriate headers to your web application that is accepting analytics data. You can learn more about this here: https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS
Essentially, your PHP script needs to know how to tell the player's browser that it is okay to send the data to your server. I haven't worked with Unity directly, so I can't give you any specific instructions, but it shouldn't be too hard to figure out how to get it working by searching online.
Hope that helps!