Missing 2G only on my Galaxy s4 I9505 on lollipop
Some Samsung devices require root access to launch the hidden testing menu. The normal code will not work in the dialer; even with ADB, you don't have access to the menu.

Since you have root access, just type the following in a terminal on your phone and the hidden testing menu should appear:

su -c "am start -n com.android.settings/com.android.settings.TestingSettings"


It may be easier through my app Root Essentials that can do this and more. You can find that test menu under "Device Info".