I have ordered a new airport time capsule, in the house we have two iPhone 6 plus a 2014 macbook pro, and a 2012 macbook air. I know the iPhones and the macbook pro all support 802.11ac whereas the air does not. When the air is connected will all the other devices drop down to 802.11n or will the rest stay at ac speed. I have a PC connected via gigabit ethernet so having ac speeds will be nice.