Protip: Disable 2G/3G fallback

[ChuckMorris]

FP2 has no setting to disable network mode fallback, meaning there is no 3G only, 4G only or 4G/3G only mode. My phone did often fall back to 2G although a (weak) 3G or 4G signal was still available. And a weak 3G or 4G signal will typically give you better performance than a strong 2G signal.

There are special apps and Xposed modules to achieve this, but I was looking for a more direct approach. You will only need root and a terminal emulator app (or ADB).

Assuming SIM2 is set to 2G and you want to set SIM1 to 4G/3G only (no 2G fallback):

su
settings put global preferred_network_mode1 12
settings put global preferred_network_mode 12,1

Reboot and you’re done.

(For 4G only use 11, for 3G only use 2 instead of 12.)

[RSpliet]

I think this setting is called “preferred network mode”, hidden in the menu that appears when you dial *#*#4636#*#* in the phone app, then press the “phone information” button. No need to be root.

[ChuckMorris]

That was my initial approach, but unfortunately this setting is not persistent (won’t survive a reboot). The solution posted above is.

But yes, using the service menu is the easier way if you only need it temporarily.