Solved! Go to Solution.
A Comcast person will most likely reply to your post to get information to ship a self install kit for the 4K DVR box.
Be aware though that the only 4K currently available using the box is Netflix. That means signing up for Netflix for 4K service. The other alternative is the "Ultra HD Sampler" app which hasn't had any thing new added for about 4 months (although they promised more on a post I made).
Things regarding 4K are moving at a snails pace here, the same as Direct tv , and Dish.