cant connect to 2g / 3g network. can only to 4g.

[Android Central Question]

i'm using LG G Pro 2 (D838). i was stupidly changing something in the hidden menu (3845#*838*), just to get 4G network. because i only get 3G.

so i started to changing things in the hidden menu, and finally i get 4g signal.
but than i realize that my phone cant be call by anyone, i think its because the signal wont move to 2g/3g network.

i've tried manually to choose gsm and wcdma only in network setting. but it cant connect.
if i choose gsm/wcdma/lte auto, it always connected to 4g.

i've tried flashing another rom, downgrade, upgrade, but nothing helps.

the funny thing is, when i went to work, my device suddenly can be called. it gets 3g signal, just in some places, but not at my home.

so i assume that, maybe its a frequency matters...

i'm using TRI (hutkinson) operator. i tried to change other sim operator. but same thing happen.

LG G Pro 2 radio band frequency
2G bands GSM 900 E-GSM / 1800 DCS / 1900 PCS
3G bands UMTS B1 2100 / B8 900
4G bands LTE B3(1800+) / B7(2600)

3 (tri) frequency network
Name Interface
900 (E-GSM) GSM
1800 (DCS) GSM
B1 (2100) UMTS
B3 (1800 +) LTE

anyone can help me out?