Iphones 11 keeps loosing cellular signal / WIFI

Hi,

I have a new iPhone 11 with IOS 13.3. I keep loosing signal bars where I have 4 bars to 1 bar to no service all in the matter of seconds. I have reboot the phone many times, reset the network settings, Restore the iPhone through iTunes and all seems not to help. I even got a new sim card from At&t store and still no help. Any assistance from apple is greatly appreciated. Also I notice my wife has the same issue on her iPhone 11 and also my brother cell on verizon that has iPhone 11 pro all loosing signal bars and disconnects like mine. I do believe this is an Apple issue. Any one experiencing same issues?