So, you have Smart network switch off and it's still switching? If that's off, try putting it in airplane mode for a bit, then on, that will refresh your network. Also, restart it.
If the advice from Iamchaos13 doesn't fix the issue you can do a few more things - press and hold the volume down button and the power button at the same time until your phone restarts, this if a quick way to fix a number of glitches and clears cache known as a 'soft reset.' If the problem continues I'd recommend going to SETTINGS - GENERAL MANAGEMENT - RESET - if this were my phone I'd do RESET MOBILE NETWORK SETTINGS and RESET WI-FI AND BLUETOOTH SETTINGS. **Please be aware that this means any Wi-Fi or Bluetooth you have previously connected to and saved will be erased and you'll need to login or set them up again BUT it resets it to essentially if you had just purchased it. Good luck!
