My D6503 just able to use 2G for call and internet, but when I switch to 3G or 4G, the signal is no longer functioning, and sometime emergency call only, sometime got full bar but can't make call or sms. I have searched a lot of threads, flashing ftf from marshmallow to lollipop, then from lollipop back to marshmallow, no luck still. Changed my sim card, try to change the apn mode, *#*#4636#*#* changed, still the same.
Anyone can help me on this issue? I have found someone encounter similar issue with me, but seem like still nobody can solve it. I have provide the link below
https://forum.xda-developers.com/xperia-z2/help/xperia-z2-d6503-gsm-signal-3g-4g-t3352837
