I was really getting annoyed that my Samsung Galaxy S5 would reboot as many as three times a day.  The reboots would occur, oftentimes, at the most inconvenient times.  One day I sat down and using my Mac laptop, I perused the Internet looking for a solution.  Nothing came to light except one weird report that some individuals thought the problem was a local cell tower problem.  I used that tip to find a few cell phone settings that might relate.  Following is my last two day notes which reveals the single culprit.

March 26, 2016,

• BATTERY:  I checked my battery for not being flat and it was perfectly non curved.
• SYSTEM UPDATES:  I checked for system updates and it is up to date.
• SMART NETWORK:  I turned off  Wi-Fi > Smart network switch to see if this is the cause.  This automatically switches between Wi-Fi and mobile networks to maintain a stable Internet connection.
• PASSPOINT:  Under Advance options (upper left corner screen options) I also turned OFF Passpoint.
• VoLTE:  Select Phone main menu item at the bottom of your main screen.  Once Phone is selected you will see 4 menu items at the top of the new screen.  Highlight the Keypad and you should see all the numbers for making a call.  To the right are three vertical dots. Press on those 3 dots and then choose the following:  Settings > Call > Call Settings.  Then choose Voice over LTE settings and then “Do not use VoLTE”.

April 8, 2016,

• In over one week, only one cell phone restart.  I was on to a solution but which of the 3 was at fault?
• PASSPOINT:  To narrow the problem down, today I turned ON Passpoint.
  Settings > Wi-Fi  >  Advanced.
• VoLTE:  I also turned ON VoLTE.
• SMART NETWORK:  This left Smart Network still turned off.  For me, this was the problem.

Solution:   From what I read, Smart network switch has had problems.  Once I turned off Wi-Fi Smart network, my cell phone only rebooted once since April 8, 2016.

This is how you can turn OFF the Wi-Fi Smart network switch:

• Press your screen Settings application which looks like a spiked wheel.
• Choose Wi-Fi once you are into the settings.
• Once you see the Wi-Fi screen look at the top of that screen and you should see “Smart network switch”.  Turn that off.  This automatically switches between Wi-Fi and mobile networks and also between 2.4 GHz and 5 GHz bands, to maintain stable connection.

Give this a try and if it does not work for you, come back and follow the above directions to turn this back on.  Good luck to you.