For Vivo and Oppo User: Step 1: Open Dialer or Call type "*#*#3646633#*#*" >Network Selection>Choose Simcard>Set to LTE only. Step 2: Open Dialer or Call type "*#*#3646633#*#*" >BandMode>Locate LTE>Check the band you want and uncheck the unnecessary band>Click SET. Then, wait for changes. Thank You!