shorewall configuration for allowing chromecast

I am having difficulty setting up chromecast on my local network. The chromecast device is successfully connected to my network, but reports it cannot access the Internet. That is not true, because I see that it successfully resolved google's servers and is communicating over HTTPS. I also see that multicast is working such that my tablet is able to connect to it. My router is running shorewall 5 (which is essentially an iptables wrapper). And, for wireless, I'm running hostapd, I don't have AP isolation enabled (the default setting in hostapd). I ran tcpdump, but didn't see anything being blocked other than I am rejecting google's DNS for my own. Is there something I'm missing, why can't the device access the "Internet".