I have 2 * Play:1 and 1 * Play:3 all connected via Wifi. I have three access points in my house, one Long Range Ubiquiti Networks Unifi Access Point and two Apple Airport Express. All APs are on the same subnet, no routing, no filtering. Everything works fine, apart from every now and then my iPhone iOS Sonos client / controller won't connect. I'm 90% sure this is when it is attached to the Unifi Access Point. I'm guessing it uses Multicast to find the Play:1 / PLay:3 devices. Reading some forums, it looks like the Unifi AP has some Multicast issues. Before I start TCPDUMPing, can someone confirm what the good communication should look like? Am I right in my assumption it uses multicast to connect? Any idea which MC groups?