Ok so what is your management VLAN on the AP switch port? Trunk port or Access Port? What is the VLAN the SSID on? If your APs are taggin the traffic the traffic is on the native VLAN.
All of chromecast /casting and printing devices are in an isolated vlan from my wireless clients. Works great but you have to enable bonjour forwarding between the two segments.
Post a simple diagram and I can walk you through what is needed but is something like this:
First I would set up my switch ports as trunk ports assign a native vlan to these ports and that is the vlan your AP will pull for Merkai dashboard access.
Allow vlans for the user devices SSID segment and the chromecast on the same AP trunk port
Tag the SSID traffic with the vlan as appropriate
Enable bonjour forwarding for the services you want on EACH VLAN.
When you first set it up it will take a couple of minutes for the discovery between the vlans, after its there its there....
Thi