I have a 2015 Macbook pro and have not found any charger cable that can connect to an iPhone 6s without incident. The behavior is a rapid connect/disconnect cycle at about a one second cadence that lasts approximately sixty seconds. After that series of cycles for some reason a steady connection is established and :

* charging starts normally
* photos can be transferred

I have tried a half dozen highly rated cables on amazon; they all behave the same way. Also both usb ports on the macbook pro  have the same behavior.


What might be happening here and is there any better fix than waiting the sixty seconds (which is actually acceptable now that I am aware of it) ?  Note that the wifi network on the macbook pro is also affected: the internet gets reset each of those times as well.