Dear Samsung Member,
Greetings from Samsung Customer Support!
We understand the inconvenience you have faced. Kindly follow the below mentioned steps to improve the performance of the device related to network:
Note: We recommend to set device network operators as LTE/3G/2G (auto connect) mode. Check device network in open area. Kindly check your device in a different location/network coverage area.
In case if the issue still persist, register your concern in Samsung Members Application for better assistance (Samsung Members App > Feedback >Error report > Attach log file for any issue)
Thank you for writing to Samsung.
Samsung Customer Support