I've tried with and without smart connect. It makes no difference. My Shield has always been set to 5ghzyou never told us whether you're using smart connect or not - could it be that the shield is switching from 2.4 to 5GHz radios based on signal strength, causing it to lose connection for a moment?
give running without it a shot, specifically naming the 2.4 and 5 GHz networks differently and see what happens. I'd be willing to wager that the issue is on the 2.4, seeing as there are so few channels in that band.