I have be use the 6121 modem with Comcast 's Xfinity internet service over the course of several month and so far everything have work perfectly with no problem . datum speed be typically 20-25 mb\/s download and 3.5-4 mb\/s upload . I buy this unit because I have read account of reset problem and other glitch experience by user of earlier Surfboard modem model , and thus far , it have meet my expectation for problem-free use . I feel the need to comment on the unit 's warmth , since other user have criticize this unit as become excessively warm during operation . maybe those user receive faulty unit , but my experience do not square with theirs ; I have put my hand on the unit multiple time to feel its warmth -- in my opinion , this unit do not become any warmer during use than any other electronic network device , include wireless router and voip adapter . I have use earlier surfboard modem -- the great 4200 and 5120 -- and I can honestly say that this unit do not get any warmer than those earlier model . it be slightly warm to the touch , but not overly `` hot '' at all , and I feel this be totally normal for this type of device . so , I be not concern with this aspect of the unit . once the modem be up and run , you can type 192.168.100.1 \/ index . htm into you web browser in order to reach the status page for the modem and view useful network statistics .