Please share the device's model number and the software version... who is your carrier?
is this happening regardless of wifi or cellular network?
if so, I would suspect hardware issue with the antenna... take it to UBreakIFix for a checkup (Batteries Plus is another option).
Otherwise you can submit error report to Samsung Members after reproducing the issue.
If it's happening on Wifi or Cellular only then try to network reset on the phone's settings, reconnect wifi (this will forget all BT connectsion too).
Additionally, for cellular only issue... contact the carrier for issues in your area.