iPhone 7 randomly not making phone calls

Hi all. I have an iPhone 7 running iOS 13.4 that has become psychotic. At random, my iPhone will not be able to answer incoming calls or place outgoing calls. It visually acts like it can. For example, if I attempt to answer a call, the screen will show that the call is active, the call timer runs, but everything is dead. Likewise if I make a call, the phone will place the call I'm trying to make, the person on the other end will see that I'm calling them, but there's no ring tone on my end, they can't hear anything coming from me, and everything remains dead. The only remedy is to power off the phone and turn it back on; then the phone will behave normally in regard to calls. But at random, the problem will return with no rhyme or reason.

In addition, when the phone works, the camera won't. I can activate the camera but I can't take a picture. If the phone isn't working, then the camera will function.

Lastly, the lightning port will no longer output any sound when I try to run an auxiliary cable from it to my car's stereo. The phone recognizes that there's a cable plugged in, but the sound continues to come from the phone's speaker instead of thru the lightning port/cable.

I have installed a firmware update hoping that would fix the problem. Sadly, no luck. I just had to replace my wife's iPhone and we don't have it in the budget to buy another very expensive phone. Is there any solution? Will a factory reset even be worth trying? I'm out of ideas.

Thanks for any and all ideas.