I try to connect it to my exist router that be also make by Linksys\/Cisco . it do not work . I call Linksys support hope that since both modem and router be by the same company , they would help . the lady on the support line tell I since the router be out of warranty , we need to charge $ 40 to configure it for you over the phone . this may include firmware upgrade as well . I then return the modem and purchase a D-Link modem . it work out of the box without require any change in my router . I be very surprised and unhappy with linksys\/cisco . first , the modem be brand new and they try to shift the issue to router . second , they build both product and there be no mention or warn that the modem do not work with older linksy router . Third , D-Link modem work without require any change in router . this mean Linksys\/Cisco break interoperability and try to charge for fix it . Linksys be now in my blacklist . when I upgrade my router - to be do shortly - , I will shop for non-linksys brand .