when my cable installer see this modem he immediately say that it would not work . I tell he try anyway , and it do not work . after he leave , I spend a while back and forth on the phone with Comcast and Motorola . finally , the only way I get it to work be to go into the modem setting through my browser and reset it to factory default . I take 1 star off for difficulty get it work , but it do boost I from about 25mbit to about 36mbit download speed .