It's not just a 4G to 3G or Wifi issue. Where I live, it's only 3G, when I go to work, it's full 4G signal all the time unless I go into a basement of a building or in certain parts of hospitals. I loose signal all the time and it doesn't reconnect, and I'm not leaving one area and going into another. I can be at my desk or house and not moving and it drops and doesn't reconnect. The airplane mode toggle used to work, it no longer does, ever. Restarting works sometimes, but not always. The other day, 20 resets at my house and I was still without any signal for the day. I actually left it off wifi just to see how long I would be with out it.
My belief is that the difference in towers from area to area as well as a software problem is making it hard for them to get on top of it. I loaded the first set of new radio/kernal upgrades and thought the problem was better, but it only lasted a day or so. I hear the same things about the latest upgrades, for some it fixes it, for others the releif is short term. No OTA until they figure it out is my guess........