EAP670 Firmware 1.0.14 ( www.tp-link.com )

From the release notes-
Fixed the bug that that multicast acceleration caused VLAN data forwarding errors.

I was having problems with Google home starting a multicast flood. Opened a ticket with TPLink, and 3 weeks later it's fixed!

I could power down the GH with the offending IP address and the flood would continue. Unplugging the EAP wouldn't always fix it either. I did some wiresharking and sent them diags, and they recreated the bug and squashed it!