I have not had to reboot my phone for this issue since my first reboot i reported. I do believe that this issue is related to Bluetooth, and here is why:
Occasionally when I am connecting to the speaker in my bathroom for when I shower, I open bluetooth and select the appropriate device, and suddenly I get prompted to connect my apple watch- WHICH I DON'T OWN. I have never had an apple watch, but it will repeatedly ask me to connect one. I didn't click on anything to indicate I have one, I just clicked on my speaker to connect it.
So, here is what I am suggesting to everyone:
1) turn off Bluetooth.
2) make sure that Do not disturb is disabled
3) make sure that Silence Unknown Callers is disabled
4) go into General, Resets, and reset Network Settings. The phone will reboot.
5) log back into phone and then manually reboot again. i know, seems redundant, but worth it.
6) test to see if calls and texts are getting notifications - this includes Audio and vibrations.
7) enable bluetooth and test with and without headphones/speaker/car connection.
This hopefully should get you back up and running, but if not, delete ALL the bluetooth devices and repeat the process again.
I am fairly confident that this is a glitch in the bluetooth build where it is not releasing its "connection" to a device, even when the device is out of range or turned off.
also- a side note. If you do not use iCloud services and plan on doing a hard RESET on the phone, back it up first through iTunes or you will lose everything. i don't believe this is a necessary step, but in case you go down this path, back up your phone first.