Dear Samsung Member,
Greetings from Samsung Customer Support!
Please be assured and to resolve "network problem" issue please follow below given steps:
1) Check Network mode and set it to Auto Connect. (Settings > Connections> Mobile Network> network mode SIM1 or SIM2 > Network mode> Select LTE/3G/2G auto connect)
2) Check device in safe mode: Press and hold the Power key, when Power off icon appears >Press and hold the power off icon.
Exit safe mode: Hold the power button and select restart on the device.
3) Reset the device: settings >General Management > Tap on Reset.
Note: Before reset make sure to have back up of the data via Smart Switch Mobile App
(Install Smart Switch App > Open > Click on Memory Card Icon >Back Up option > Choose the data for Back up > Back Up).
If the issue still persist, kindly register your concern in Samsung Members app (Samsung Members app > Get help > Feedback > Error report/ask question).
Note: Please send device log files within 15 minutes of issue occurrence along with the exact issue details.
Thank you for writing to Samsung.
Samsung Customer Support