buy it for my the comcast cable internet . Comcast have certify this . and the box in which this come boldly display the certify by comcast mark . but it barely work I keep have trouble like lose connection and finally one day it completely stop work . the Comcast technician who visit my place tell I many other people face the same problem with this one but Comcast refuse to officially remove this from the list of certified modem . finally now I be use a surfboard and it do not have any problem .