it goes against my principles to recommend this, but it worked so well I must help by offering it.
I purchased a dual band router and hung it off the Xfinity router.
i have excellent throughput anywhere in the house.
I can run streaming audio or video (hbo go, showtime anytime, you tube, netflix) without interruption or buffering, on either 2.4 or 5 ghz.
I am a gamer but because I am on the road I am not gaming with this connection.
While we should not have to buy something to fix this problem, it ended my frustration, and I finally appreciate what my new laptop has to offer.
It is clear that the problem has something to do with the Xfinity router as well as Intel's inability to write a driver to compensate for a router that so many people have in their homes.
Best Buy suggested that I try the router, based on their knowledge of Xfinity routers and the fact that if it didn't work I could return the dual band router, no questions asked.
I have yet to try this laptop on Uverse, but next week I am heading back to where the Uverse router connection will get tested.
If you can buy a router under the same return policy conditions, you might do as I did and give up on waiting for Intel to resolve this.
As with problems in interfaces, you are dealing with many variables. Looks like you bring W8.1 into the interface as yet another suspect component to be taken into account.
I am running 8.1 from the time of my purchase so I wouldn't have known that difference.
The plot thickens!