PProblem using parental controls behind Comcast Router

Just picked up a 3700V2 and wanted to enable parental controls, but once I do I lose the ability to get on the Internet.

My setup:
Comcast Business

Internet --> Comcast SMC Router -- > 3700V2 ---> Netgear gigabit switch

Comcast LAN:10.1.10.1 3700 WAN:10.1.10.2 3700 LAN:192.168.2.1

I enabled DMZ on the Comcast router to send all traffic to the WAN port of the 3700. I also disabled the firewall and smart packet detection on the Comcast router. As soon as I enable parental controls the Internet goes down. To get back on I simply change the DNS settings on the 3700.

Any idea on how to make this work?

Thanks,
Jerry