about a week ago I upgrade to Comcasts Extreme 50 internet service however my old rent modem that I use with Performance internet be only give I about 25 mbp down so I go to Comcast & swap it for a new Cisco modem . hooked that up & I have the full speed I pay for . meanwhile I check Amazon & find this sb6121 & it take a week to get here . hook it up , go through the activation page & now I be get 61.71 mbp down & 11.52 mbp up which be the same speed I be get with the rent Cisco modem . Yay , now I can give the rent modem back to Comcast !! I would not hesitate to buy this modem again as it be really a good one for the price . Update : 6 week later & this modem be still work great . the service outage I be get with the old rent modem have disappear . the sb6121 have yet to lose it be connection to the internet . get this modem . you will love it !! oh & the online activation be a breeze ...