ZyXel EMG3425 Router: Chromecast Issues: Chromecast Won't Connect to Any Devices

If your Chromecast can connect to the Zyxel's wireless network, but no devices can talk to it (e.g. Unable to cast from laptop to the Chromecast):

1. Log in to the Zyxel via IP address. (Open any browser and navigate to 192.168.1.1. The default username is admin and the default password is 1234.)
2. Under Settings > Network > WAN, most of the way down the page, you'll see Multicast Setup.  The default is set to None. Change it to IGMPv1/v2.
3. Reboot the router. It may take 3-5 minutes for the router to come back online. 

If you are still experiencing issues after that, please don't hesitate to reach out!