I have be through 3 Motorola Surfboard sb6121 modem within the past 2 day . purchase product at local retailer . before I upgrade to the Docsis 3.0 modem and package , I be use the Motorola Docsis 2.0 12 mbp down\/2 mbp up package with Comcast . with the Powerboost feature the device average 19-20 mbp down\/4 mbp up . after the upgrade to the Docsis 3.0 and 20 mbp down\/4 mbp up package , the new modem average speed of 30-31 mbp down\/1 -2.5 mbp up . there be time the device would peak at 3 mbp up , but that be a best case scenario . as you can see , this be very frustrating know that you upload speed be not at least on par with you old device and performance package . several folk from Comcast state that the signal strength and ping to the Docsis 3.0 be good . however , one tech do a line test and the result come back that a tech need to be send to the residence . the tech come out and find nothing wrong with the line . the Docsis 3.0 continue to give a dismal performance while the tech be present . he test a Arris Docsis 3.0 modem he have in the truck and it perform flawlessly ; 31 mbp down\/4 mbp up . the device he have perform as it should . BTW , from what I can tell `` yes '' the tech on the phone and at the residence provision the device correctly . I take back the modem I have to the store and pick up another one . the second modem could not be see on Comcast 's network so I hurry back to the store before it close and pick up another one from another location just in case I be pick up modem from a bad batch . needless to say , the third modem perform the same and I now have the old Docsis 2.0 back on the network . I be back to get my great speed . BTW , I also test to see if there be any difference in speed between the 2.0 and 3.0 with the Playstation 3 . the 2.0 still outperform the 3.0 . I just do not know what it be with the 3.0 . it be as if this device will work flawlessly for most people who may or may not be aware of they speed before upgrade . however , I be not impressed enough to keep the Docsis 3.0 .