I am using MTNL mumbai 3g card..after setting LTE as preferred network, i should get 3g network whenever available. but if the 3g network is weak then it automatically selects 2g network. but when 3g network is available, it should automatically switch over to 3g from 2g. But each time, i have to manually select 3g network by manually searching the mobile network.. it is very time consuming & frustrating..