CyanogenMod 13 fall down to 2G when data connection is OFF I'm new to Android 6 and I'm coming straight from 4.2. 
As my region is with lower celluar network coverage, I'm experiencing problems with my network coverage. Now, the problem is that my Galaxy Note 3 is loosing 3G signal, because the 2G is more common here and 3G is avail only in the city. I can't select "3G (preffered)", like I was able to do in Android 4.2, then when I turn on the Data Connection, the phone will switch to 3G, when I turn it off, it'll go to 2G. I can't do that on Android 6.0, and the phone is in HSDPA all the time.
I am using cyanogenmod in my Xiaomi Redmi 1s, I used to do this steps :


Open dialer, and type *#*#4636#*#*.(I think this setting code may vary with each device manufacturer, search appropriate code for your device)
It will enter into Testing mode.
Inside that, tap on Phone Information, look for Set preferred network type, and set it as WCDMA only.


This Setting will be lost after every reboot.