Iphone 6+ USB disconnects from Macbook Pro constantly over and over
Try the following command in terminal:
sudo killall -STOP -c usbd
Apple designs their hardware to request and signal for more current to iOS devices than the USB standard allows.
The usbd process manages this. If you kill the usbd process, it stops trying to send high current and will treat it like a non-iOS device and send a normal 500mA of current, and your device should stay connected.
reference: iPhone-Mac connection issue and what does the usbd process do?