I be not pay attention . my bad ! have I realize , I might have be write this review many , many month ago . first , a little research ! my modem from Comcast be model #sb 5101 -lrb- Motorola -rrb- DOCSIS 2.0 , and it work just great for those 3 year + of service , never a hitch ! ignorant enough , and a shock to my system ... to learn I be `` rent '' they equipment to the tune of 7.00 monthly . now ... I immediately bulk , the feeling of be rip off by a company who give no quarter to they `` veteran '' subscriber . a list of they `` approve '' modem easily discover at -lrb- comcast.com -rrb- the `` math '' be easy enough too ... within less than a year , my new Motorola would put I back into the `` black '' . there be literally no learning curve to this process of exchange , a no brainer ... that be , if you can read ! -lrb- g -rrb- the procedure be just as these other have state . turn everything off , change you cable a bit , bypass you router -lrb- if you have a network -rrb- , plug everything back where it be , boot you computer , and immediately , as you punch in you browser ... a page from Comcast come up ! be sure you have you account number in front of you , and you phone # of record . for I , the Mac ID be already there , do not have to type it in at all . they will automatically set up the new modem in just a few minute . really simple ! read these review ! some be very helpful if you be a comcast customer ! just be sure you take note the old fashion way ... pen and paper , before you disconnect you old modem ! this Motorola , sb6121 , do not run `` hot '' , at least not for I . it be barely warm . as the review attest , it run faster , much faster !! the detail be there also , in these review . you can believe they . the `` hardest '' part , this whole procedure ? the return of Comcast 's property . you must find the nearest Service Center to return it ! if you request a service tech to come pick it up , they be go to charge you plenty ! and ... whatever you do ... . . get you receipt as evidence you return it ... save it , and keep check you itemized bill . I do not trust they ! you might . : o -rrb- would not you think ... the money we pay they , these very necessary `` extra '' would be include ?? bummer ! my next project ? this hd receiver box , another dumb rental ! Amazon , here I come again ! -lrb- g -rrb-