I agree. I activated mine with the online live assistance of a Comcast adviser. I did the initial activation with my Macbook connected directly to the Arris SB6141. After ending the chat, I attempted to connect wirelessly via an Airport Extreme that I had just connected to the modem. I fiddled with the settings of both units for hours until I decided that maybe a cold restart of the modem might be in order.
What disturbed me most about this was the fact that the Comcast adviser did not instruct me to perform this reset as she knew that I was going to connect a router to the modem. Maybe Comcast should add this important item to their cheatsheets that their advisors work off of?