I am STRUGGLING with this. Spent hours in my router trying to get multicast working across interfaces. The frustrating thing is that I have the IP address of the light, but there’s no way to give that info to the integration. The multicast is only needed for IP discovery, and according to the local API’s documentation there’s no real need for multicast once the IP address has been communicated. It’s so frustrating, because the lamp I got (Govee Floor Lamp 2) also has Matter support, but getting Matter to work across interfaces is ALSO an absolute nightmare. Stick to Zigbee/Z-Wave/ESPHome, kids.