Hey! Could you please tell us your OS build ( Settings > System > About ) ?
> Signs of software(OS) problem
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Before starting this discussion, have you tried:
Soft Reset (or Reboot) of your phone ?
Re-insert the sim cards ?
Are you using Windows as insiders ?
If problem still occurs, then you should do a Hard Reset (after backup your all personal data from Phone memory and remove your SD Card before taking this step).
Let us know what will happen after trying the above.