I buy one of the refurb unit . plug it in , call Cox cable to give they the serial and MAC number . they reset . I reset . come up perfect . I have about a 10 year old linksy modem and be get speed of around 17000kbp down and 2000kbp up . not quite what be claim . cox say I should be get 22 down and 3 up . now with the refurb unit I be get 32633kbp down and 3725kbp up !!! my older modem be hold my speed down . this happen when Cox double the speed in a effort to combat Verizon Fios in we area . I be sure they change some specification regard the way they signal go through a modem . I have see that before . when you speed get whacky and you have to reset you modem several time per week , -lrb- my first clue -rrb- , they have change they signal . you old modem be fine , just outdate . so , if you have a older modem , better spend the less than $ 30.00 and get this good one . no problem here .