http://forum.xda-developers.com – I have AT&T Galaxy S4 32gb running lastest firmware MDL. (stock rooted). Today I randomly lost any data going to my phone. It still showed I was on 4G with 3-4 bars but I tried to open Pandora and it would not connect, I also tried going to the PlayStore about 45 minutes later and it did not connect. I disabled Mobile Data and re-enabled it and all is working fine. (HowTos)