I buy the sb6121 , because Comcast 's list of approve broadband modem ; show this modem be approve for all speed tier . I do not want to be charge $ 7 for use they modem . it be not cheap , but of coarse you get what you pay for . this model of modem be not find at consumer electronic store . have a XBOX 360 connect to this modem 's online gaming capability feature . no problem , at all in this area . I be very satisfied with the sb6121 . one complaint I have about this modem be that it be assemble in China .