[Q] Make 2G to work topic

In sense roms I only had bug of freeze data when switching between 2g and 3g, but both networks worked. Then I tried AOSP 4.4.4, and my main problem was a lot of com.android.phone force close, then I lose signal. Finally I saw the problem was when autoswitching from 3G to 2G (and dont know a way to "force" 3G only) then I decide to go to Lollipop, everything was better, when the phone automatically go to 2G, I still can make calls (but with a bug that I need to reboot because i cant hang up) but still, cant get data in 2g, if I select 2G, there is no mobile data, or if the phone go from 3G to 2G, no mobile data, just in 3G.

So, any idea? I tried to flash 1.35 Radio with extra partition, nothing, I return to 1.20 radio with extra partition and nothing. I'm on cm12, hboot 2.16 and radio 1.20 right now, and still no idea what can i do. I tried a simcard from other operator, and still the problem so is not the simcard.

Any help would be great.