when I get the cable modem I connect to my network and I be ask by comcast website registration for some datum , but I could not do anything without the customer number . and the modem be resete itself every time I send datum . so I get the web page and when I submit my router to register the modem get restart . I think it be in bad shape but I call comcast and they add it with a wrong Mac address so I be plane to return it . it would work if it be no mistake by the comcast person add the wrong Mac address . I read that issue in some review so I believe this people think there be something wrong with the modem , but after try again for a couple time the datum go through comcast website update the mac address to the correct one , once this be set the modem restart for the last time ! and since then I have not have any issue problem performance etc with it !