This is an FYI for anyone that is using grandstream wifi access points. I have mine happily working with sonos. I have 5 gwn7664’s that are hardwired to my pfsense firewall/router running in bridge mode. pfsense hands out the ip address. I made 2 changes to the ssid configuration:
ssid → edit → advanced:
Multicast/Broadcast Suppression: disabled
Convert IP multicast to unicast: active mode
And now everything works! All sonos speakers are running wirelessly.