updated 11:20 pm EDT, Mon June 24, 2013
Service technicians advised to replace troubled gear, send defectives back
Apple's 802.11ac wireless launch has been somewhat less than perfect. In an effort to diagnose problems reported in some new Apple devices sporting 802.11ac compatibility, the Cupertino manufacturer has instructed its service centers to "capture" customers' computers if they are suffering from Wi-Fi connectivity issues. Additionally, technical research has been published noting that Apple uses a sub-optimal network setting built into the wireless protocol, limiting the connectivity speed of the new standard at least temporarily.
AnandTech took an in-depth look at packet sizing in the new Airport in both OS X and Windows, and found that the max packet size is restricted for maximum 802.11n speeds under OS X 10.8, limiting the transfer rate of 802.11ac gear. This is fixable with either a software patch or an OS revision in the future, however, so it may be a short-term issue.
MacNN has learned that Apple is aware of the limitation, and a new OS X 10.8 revision will be promulgated soon with a patch for the issue. Under initial test circumstances, throughput on 802.11ac has been shown to be more than twice the 802.11n standard speeds.
Reports began circulating shortly after the new MacBook Air line hit store shelves about the 802.11ac not living up to its full potential. There have been reports of sporadic connectivity with some units, not only with 802.11ac devices, but with 802.11n base stations as well. Apple service centers, when confronted with the issue, have been instructed to collect the user's machine, replace with a new unit for the customer, and send the afflicted machine back to engineering for testing.
MacNN Labs has begun evaluating a new 2TB Time Capsule with 802.11ac support in conjunction with a new MacBook Air, and have experienced similar failures to that reported on the Apple support forums. Apple has requested the Time Capsule unit we purchased for testing be returned because of sporadic connectivity issues. Testing will recommence upon replacement.