This probably isn't a firmware issue. All of my Intel 620x adapters work in 2.6Ghz. 802.11n is definitely problematic, but we're not going to get a Maverick fix from Intel.
This probably isn't a firmware issue. All of my Intel 620x adapters work in 2.6Ghz. 802.11n is definitely problematic, but we're not going to get a Maverick fix from Intel.