Go ahead and uncheck your connections optimizer box again after you do that go back into settings -> wireless and networks -> more settings -> mobile networks -> network mode -> change preferred network mode to CDMA only. Please make sure your connections optimizer is unchecked first then go in and change to CDMA only your phone will then reboot.
Let me know if this changed anything.
Social Care Team
If it keeps coming back, then you will need to Disable it.
Select Disable in the upper right. Shouldn't come back after that unless you get another update.
Not sure which phone you have but check the following or round about,
Turn it off.