I was trying to download an app that was about 3 mbs and it wouldnt download. It would show the spinny bar but it wasnt actually downloading. It finally downloaded while I was in wifi. This was the same case with downloading pdf files and really anything that involves downloading. I am currently using the galaxy s4 on the AT&T network. The thing that is weird about this problem is that I can surf the web and do anything else that requires internet on mobile data its just I cant download anything over mobile data. Any help would be greatly appreciated.