Since I only have one ethernet out on my modem, how would I connect both the pc and the SB for a test?
You then need an ethernet switch.
Your M1000/W1000 presumably is filtering multicast packets by default and you can't change that setting. As others have experienced the same issue (please see this thread in the Qwest forums), you should consider dumping the W1000 and purchasing a new wireless access point/router.
Greetings
dupondt