I am also facing the same issue, i have Cisco-2504 wireless controller and not able to find the option to disable the AP isolation mode. Want to know how to disable ap isolation mode.
Below are the solution provided by chrome cast community,
Troubleshoot an Issue
Please let us know how we can help you:Setup: I'm having trouble setting up Chromecast
You'll need a phone, tablet, or laptop computer to set up Chromecast. You can set up Chromecast by first navigating to cast.google.com/chromecast/setup. Tell us a little more about where you're having trouble:I can't connect to the Wi-Fi network that I'm selecting
I'm seeing the following error, "We cannot connect with your Chromecast from this computer"
Please note: You may need to change your router settings before Chromecast can communicate with your network. Please refer to the Chromecast router compatibility page for more information.
Which of the options below best describes your issue?
Here are some things to try:
If you have a dual band router, ensure that AP isolation/client mode is disabled. This may require a small change in your Wi-Fi router settings. Please visit our AP Isolation mode page for help troubleshooting this issue.
Enable Multicast, UPnP, & IGMP in your router settings.
If you’re running DNS software, enable the following public Google DNS IP addresses: 18.104.22.168 & 22.214.171.124
If the router/network on which you’re attempting to set up Chromecast has AP or client isolation enabled or a captive portal (typical of hotel rooms, school networks, corporate environments), you will not be able to set up your Chromecast device properly. See the section related to traveling with your Chromecast in the FAQ.
Your Wi-Fi network configuration prevents devices from communicating with Chromecast. In order to resolve this issue, you will need to disable AP (access point) isolation, AP isolation (also known as 'Client Isolation' or 'Guest Mode'), on your router. Please refer to your router documentation to learn how to disable AP isolation.
If you do not have access to your router settings, or if you are attempting to connect through a guest, hotel or public network with AP/client isolation, you will be unable to set up your Chromecast.
If you are attempting to connect through a Wi-Fi extender, please check your extender settings. You will need to disable AP isolation on your Wi-Fi extender before setting up Chromecast to work with your Wi-Fi network.
Have you guys been able to resolve this ? I am sort of having issues with chromecast. Have enabled Multicasting and mDNS on controllers. Can see Chromecast connecting to SSID and network but that's as far as it gets. When I try to setup the device it fails with the devices cannot talk to each other. .. Any help is appreciated..