I am also facing the same issue. My calls gets disconnected, after making a crackling noise and then signal goes off. Mobile signal goes off at random interval. Auto restarts happen frequently...
Dear Samsung Member,
Greetings from Samsung Customer Support!
We acknowledge your query and apologize for the same. To resolve your device network issue please visit this link: https://www.samsung.com/in/support/mobile-devices/samsung-galaxy-smartphone-how-to-optimise-network-...
In case the issue still occurs. Please register your concern in Samsung Members Application (Open Samsung Members Application > Get help > Send Feedback > Error report/Ask questions).
Thank you for writing to Samsung.
Samsung Customer Support