[Q] Need to change LTE band of LG G2 D800 AT&T topic

I need to change LTE bands for LG G2 D800 AT&T. I have tried selecting LTE band 3 in Hidden Menu but that did not help. I live in Pakistan and LTE band 3 (1800 MHZ) operates here. Or is it possible to change the radio of my phone? Or shall I try flashing a LG G2 D802 ROM on my phone? What would help?
Can someone please help me?