Cisco 3802 not forwarding IPv6 multicast to its clients

[ProTofik]

Hi,

My WiFi access points are Cisco 9120AXI and Cisco 3802 in FlexConnect mode, with the 9210AXI being the embedded wireless controller (IOS-XE 17.15.3), and 3802 being in lightweight mode. Both are connected to the same Cisco C3560CX-8XPD-S switch that acts as a L3 gateway for both IPv4 and IPv6. The configuration of both switchports the APs are connected is identical.

When a client (tested with Windows 11 and Android 16) is connected to 9210AXI, IPv6 works flawlessly. When they're connected to the 3802, they don't get IPv6.

After I bit of troubleshooting with wireshark, I noticed that 3802 is not forwarding IPv6 multicast traffic to the clients. I confirmed that the traffic arrives at its switchport by doing port mirroring. No IPv6 multicast means no router advertisement, and hence the devices cannot do SLAAC. 

What could be the the reason for 3802 not forwarding IPv6 multicast to its client while on the same network, 9120AXI works fine? 

[Rich R]

Not something I've tested before but have you looked through:
https://www.cisco.com/c/en/us/td/docs/wireless/controller/ewc/17-15/config-guide/ewc_cg_17_15/m_mdns_gateway.html
and 
https://www.cisco.com/c/en/us/td/docs/wireless/controller/ewc/17-15/config-guide/ewc_cg_17_15/wlans.html#restr-wlans
Section Configuring General WLAN Properties (CLI)

media-stream multicast-direct

[ProTofik]

Thanks. I enabled media-stream multicast-direct but unfortunately it didn't work. Devices connected to the 3802 still do not get IPv6.