I don't know whats going on, but my phone constantly drops 3G all the time and when I go back and check the mobile connection it says disconnected...then I have to shut it off and turn it back on but most of the time it doesn't come back on right away.....no 4G comes up either. It's really frustrating. I changed the settings to do CDMA only but it still drops the 3G. It has done this since the day I bought the phone brand new at a Sprint store. I see where people say to turn the optimizer off, but I can't find that option anywhere. Even under Apps, All apps....nothing is there that says optimizer in order for me to shut it off. Thanks!
You will want to go into your settings, then go down into apps click on that, you will have 4 options tap on the last one that say All scroll the list till you see Connection Optimizer tap on that one then, next to force close you will see disable tap on that one. And that should help you out. And Diable it and it been doing good so far.
Try the following,
Then press the Search button (magnify glass at the top). Soon as you get the first 3-4 letters of Connection typed in, it should show up. Select it, Press Force Stop and the Disable to disable it.