[Q] question for LG G2 sprint version topic

Dear friends, my friend bought a second hand LG G2 sprint version from olx India. The phone is unlocked already and its rooted also. But the problem is in some sims, the internet doesnt work but the network is there..(data is not working).

Will installing custom roms solve the problem?? I have done the permanent sim unlock for LS980(one thread is there for it).

Currently on:
Android Version: 4.4.2
Software version - LS980ZVC