I have the Motorola SBG6580 as a cable modem. Same issue, only computer could connect to the internet. Got the following suggestion on the Charter Internet/TV board.
said by cablegeek01:
That 192.168.100.1 IP address on the SBG6580 could be causing a conflict since that can also be used to access the internal web page of the modem itself (not the gateway). try changing the LAN IP on the SBG6580 from 192.168.100.1 to something like 192.168.25.1 (255.255.255.0). reboot the modem, and reboot all your devices. Verify that they now pull a 192.168.25.x IP address and see if it can get online.
That hint helped me solve the problem. Here is my answer. Hope it helps.
said by NotVariable:
That last suggestion did the trick. I changed the LAN IP address to 192.168.100.2 and changed the DHCP range to exclude that address. Also, it works with the Firewall turned on.
I initially changed the IP address and DNS settings on the Blu Ray Player to get the connection to work, but was able to change it back to Auto so that the SBG6580 supplies them thru DHCP.