You most likely activated a battery/data saving feature. Go to settings>battery/data manager. Make sure you don't have data saver activated. If that's not it pull up your market and check the settings. Make sure you don't have download over wifi only enabled. It can also have something to do with how you are using smart actions. Being that I don't have a D4 I can't offer insight on that. Hopefully what I mentioned will help you out though