I work in a area that just barely gets 4G service. The issue I am having is the phone will lock onto 4G, but not move any data. It will just sit there with the 4G icon at the top of the screen without the arrows lit up. It will not switch over to 3G. If it does start out on 3G, everything works fine for a little while, then it will switch itself to 4G and stall. Any suggestions would be greatly appreciated.