I was never able to consistently use my 6 Plus connected to my Time Capsule ac model over 5Ghz ac because of the weak wifi antenna system in said 6 Plus. With the 6s Plus? Everything is quite different, and I can finally use 5ghz two floors up from the router with great success! Everything loads very snappily. Using the free app Wi-Fi SweetSpots, the difference in connection speed to the router is consistently 2-to-3 times faster on the 6s Plus versus the 6 Plus. Guess which is which? Also, the 6s Plus is in an Apple case for this test, and the 6 Plus is naked. Both tests run individually.