I've also tried all 3 installed kernels with the same result: Flakey wireless
When I bring up the connection details (which takes to many clicks/menus) I see connection speeds of 1, 18, 24, or 54Mbit but this is a n device and has connected reliably at 108Mbit before now and the AP is less than 20 feet away.
Sometimes connections get stuck at "resolving host" and other times it works.