I have purchase this modem to replace a lease modem from Comcast . I be on the phone with Comcast for less than 20 minute and everything be up and operational . after successfully get this modem up and run for about a day or so , the modem some how be power down by itself and it never come back online again . no led or power on the box . I have the modem return to Amazon for full refund and decide to give SBG6580 DOCIS 3.0 \/ WIFI\/Router a shot . I be not disappoint at all , because I still have the dsl as a backup connection until the new replacement modem arrive . 1 , attach the coaxial cable to the modem , 2 , power it on 3 , attach the one end of the LAN cable directly to you computer and the other to the modem . 4 , if you get the 192.168.1 . x address and no default gateway set , then it be time to put a call into Comcast . 5 , before call Comcast , take down the HFC MAC address from you modem . 6 , all the light should turn green once Comcast have activate it successfully . 7 , if you be still get the 192.168.1 . x address from the modem via DHCP . here be the fun part , which Comcast technician do occasionally ask they customer to do in order to resolve the issue be by reboot they pc . I do not see there be a need for reboot you pc , just detach the LAN cable from you pc or from the modem end and re-attaching it again . you should see the 76 . x.x. x -lrb- comcast public , could be different for other carrier -rrb- address obtain on you pc . this have indicate the modem be now in bridge mode and be fully functional . 8 , open up a terminal window and try to ping -lrb- ... -rrb- or 8.8.8.8 . if you see the ping response , then you be good to go . if you be not computer wiz , then just bring up you internet explorer or browser to test you connectivity . 9 , speedtest you connection too by go to -lrb- ... -rrb- before let Comcast tech get off the line . 10 , now you can disconnect the LAN cable from you pc and have it plug into you home router\/wireless WAN port . good luck everyone and hope I will get better luck with sbg6580 .