Ok SB 5 Series modems are stand alone modems.
One way to check is to look at the status/device info web page on the router. Look at the WAN/Internet section, if it say 192.168.0.# then the router is getting a private IP address, if something other than 192.168 then your getting a public address and your fine.
Some things to try: - Log into the routers web page at 192.168.0.1.
Use IE, Opera or FF to manage the router.Turn off ALL
QoS or Disable Traffic Shaping (DIR only) GameFuel (DGL only and if ON.) options. Advanced/QoS or Gamefuel.
Turn off Advanced DNS Services if you have this option under Setup/Internet/Manual.
Turn on DNS Relay under Setup/Networking.
Setup DHCP reserved IP addresses for all devices ON the router. Setup/Networking. This ensures each devices gets its own IP address when turned on and connected, eliminates IP address conflicts and helps in troubleshooting.
Ensure devices are set to auto obtain an IP address.
Set Firewall settings to Endpoint Independent for TCP and UDP under Advanced/Firewall.
Enable uPnP and Multi-cast Streaming under Advanced/Networking. Disable uPnP for testing Port Forwarding rules.
Set Time and Time Zone under Tools/Time.