One thing that I should mention about the Comcast gateway - it puts out three Wi-Fi signals, all on the same channel. One is the normal SSID that is used for connecting to the router by the user of the router. A second signal has an SSID of XFINITY and is used by Comcast to make Wi-Fi hotspots available to other people who can pick up the signal and have a Comcast account (this is something that Comcast has been rolling out this year and is now available across the country). The third signal has no SSID (hidden network) and is also on the same channel as the other two (channel 11 in my case) - so far I have not been able to determine the reason or use of this third signal.
Comcast does not allow the end user to control these "extra" Wi-Fi signals. The only thing that I can do from my end is to determine the channel used (all three always use the same channel). Since there are literally millions of these Comcast devices across the country it is something that Intel needs to learn how to deal with with their network adapters (both hardware and software).
As mentioned in my initial message, the Gateway device that I have is manufactured by Arris and is model TC862.
My Intel 7260NGW AN has no problem at all with my Cradlepoint router - good connectivity, never drops the signal and excellent download speeds. It doesn't seem to matter at all which Intel driver I use, all of them seem to work fine with the Cradlepoint router.