I have have a Motorola sb5100 for 7 year and never have any trouble with it . after 7 year I figure it be time to upgrade so I decide to buy a sb6121 . it be Motorola it have to be good right ? wrong . it come and I connect it to my cox cable no problem and it work great , for about a day . the speed be noticeably faster than the sb5100 , but then I get a error message say I have no internet connection . I think in my 7 year with the sb5100 I might have get that message 7 time . I look at the sb6121 and all the light be off . it do not seem like it be get power . I check to see if it be plug in and it be . so I unplug it and plug it back in and it reboot no problem . long story short it keep do this for a couple of week and sometimes it would reboot and sometimes it would not reboot until after many try or many hour . I call Motorola tech support and we do a factory reset on it and that do not help . the Motorola tech say it sound like a hardware problem . unfortunately , since I do not buy it from Amazon I could not return it . that $ 10 I save do not look like such a good deal now . so I go back to my 7 year old sb5100 . this seem like a good , fast modem while it work but unfortunately that be not very long . I have read a few review which say they have the same problem but I just figure they have get a lemon . I would like to get another one but I think I will wait awhile and hope Motorola fix what seem to be a too common problem .