Solutions that i know
1. Reset network setting
2. Clear cache partition of you device
3. Reset APN and set DNS to automatic
4. Insert you SIM Card in slot 1, enable data roming and select 2g/3g/4g auto
5. Turn off data saver and battery saver
6. See attached file(photo), set data limit to as maximum
7. Factory reset (last solution)
Note:- after doing step 3 or 4 just restart your device.
May it help🙂
