Take a look at the Traffic Filter for the Network Policy. If you are using the default traffic filter and haven’t made any changes to it, you shouldn’t need to do anything. But if you are using a different traffic filter, make sure the “Enable Inter-station Traffic” setting is set to true. If this is disabled, it won’t allow wireless clients to communicate with each other.
Also, check to see if you have any IP Firewall Policies set that “Drop traffic between stations”.
Lastly, are your clients and the Chromecast on the same VLAN? Because if they aren’t, you will need to look at your Bonjour Gateway setup and/or router setup to make sure that multicast is being forwarded.
