I receive the sb6121 in about 2 day with Amazon 's excellent packaging . hook-up be a snap until I get to assign the MAC number with Comcast . we try several time to sync the new modem with no success . I then take off my glass and use a magnifying glass on the MAC address tag . I then find that `` b '' be really a `` 8 '' , and `` D '' be really a `` 0 '' .  so much for the golden year . have I read the number correctly , syncing would have take about 3 minute . we do a quick test and I be pull over 21.0 meg . I go ahead and buy the 3.0 docsis to try to be ahead of the curve . this dummy have be pay rental rate for year and should clear the cost of the 6121 in a little over a year . excellent price , free shipping , and prior Motorola experience be all buy factor .