ARRIS/SURFboard → SBG6782-AC intermittent disconnect

I have an SBG6782-AC purchased for use with Comcast service. I am using both the modem and router funcitonality. The connection seems to work fine without significant errors noted in the modem's log. I don't have any issues with 2 iPhone 5's or 2 iPad 3's, connected to either the 2.4 or 5 GHz networks.

However, my laptops - a personal Vostro 1520 and a work Lenovo T430 with internal Intel adapters - seem to have a lot of issues with intermittent disconnects (the wireless icon shows it is connected, but with the yellow exclamation mark and message stating "No Internet Access." During these times my iOS devices connect to the internet just fine, so it doesn't seem to be an ISP or modem issue.

How can I figure out what's going on with the laptops?

I believe the connection status on your laptops to be from a windows update, not the router/modem.

If your gateway allows, set a static IP for each device.