Please reset network setting of both Sim one by one and than reset all settings of your's device in general management settings also Flight ✈️ mode on n off one time, restart your's device without any Sim in slots, interchange Sim in slots, turn off power saving mode then try to it's again. If you like please accept as a solution it's help to others users also, click 3dots in my reply section and click on accept solution. Thanks.
In case the issue still occurs, please visit the service center for a physical inspection of your device. You can locate your nearest service center with this given link: https://www.samsung.com/in/support/service-center/
