Has anyone else had issues with the newest MBA wifi? It's my wife's computer. I have all of the OS X updated fully updated. I'm using a Netgear R7000 802.11ac router, and I'm having this issue on my wife's macbook air. I have a rMBP (non-AC), and it can connect on both the 2.4ghz and 5ghz bands without any issue at all at much higher speeds. My transmit rate right now on my MacBook Pro is 217mbps. When I got to the MBA right next to it, on both the 2.4ghz and the 5ghz band, the MBA is capped at 54mbps. Additionally, when I option+click on my pro, it shows me the "MCS Index" underneath the transmit rate. On the Air, the MCS Index is not shown. Does my wife have a defective wifi card in her mac? Is something else going on? Thanks!