2 separate Zyxel APs connected to Mikrotik on 2 ports (Eth2 & Eth3)

Scenario 1:

Chromecast --> Zyxel NWA1123-ACV2 --> RB2011UiAS ETH2

If I connect laptop via Zyxel NWA1123-ACV2 (any SSID, either 5 or 2.4 Ghz) there are no issues to cast (Chromecast is visible & accessible)

Scenario 2:

Laptop --> Zyxel NWA1121-NI --> RB2011UiAS ETH3 (same network as above , just another AP in a different part of the house connecting to another port on Mikrotik RB2011UiAS, both ports Eth2 & Eth3 are part of the bridge)

I can ping Chromecast, but it is not available to cast to.

Obviously multicast is being stopped at Mikrotik. It makes no sense, as ALL devices ARE on the SAME IP range

The only way I could get it working was as per this
Anybody has any idea what is going on?

sebus

I have several chromecast connected to my mtk routers and i have no issues

HOW WONDERFUL FOR YOU!

But if you have nothing to add then do not bother to post?

Why do you assume:
"Obviously multicast is being stopped at Mikrotik. It makes no sense, as ALL devices ARE on the SAME IP range"

It worked with MT and the first AP. What is new now is AP2.
Just to be sure you could plug AP2 in eth2, and try to reproduce.

Back to the issue, it may be related to ARP. IP-to-mac mapping. Do you have any arp filter along the way. Are all interfaces including your AP's in arp=enabled mode?

I am not assuming anything.
On same AP no data ever travels to the Mikrotik, as it is all on same AP

Swapping the APs makes no difference

Yes, arp is enabled on all interfaces

sebus

I understand that you have your chromecast on ap1 and client sometimes on ap1 and ap2. AP1 - AP1 works, but AP1 - AP2 doesn't.
What is new / extra in second case:
* ap2
* client itself

Have a look at their configuration wrt multicast processing.

Same client (same laptop connected to either AP)

AP2 is not an issue, as if I connect Chromecast to it I am in same situation. It is Mikrotik issue
(which I can sort as per first post, but do not think it should be so)

sebus

Please list your MT config