Just a heads up for anyone using the UniFi (Ubnt) wireless network APs / UAP things (possibly other similar setups as well)
While I love my UniFi kit I was having a problem with my Sonos. After kitting out the upstairs my Sonos controller on my phone was only picking up 3 out of 6 when I was downstairs, then the other three when I was upstairs.
Now you can probably guess what was happening already but the above is a very simplified explanation of months of the controller not picking up any Sonos devices or 4, or 5 - it all appeared to be very random.
Anyway, what was happening is that the controller was only showing the Sonos devices connected so the same AP. Despite the fact that every other aspect of my network working (I can even carry a Skype call between the two APs) the Sonos devices were obviously can't communicate with the controller on a different AP for some reason. It didn't help that they kept changing which AP they were connected to every so often (with the other half turning them off/on, power cuts or me turning the power in the house on/off as we do some renovations).
So yeah, while a Google around suggests other people are having the same problems and have modified some of the UniFi AP settings to no avail the quickest way I found to resolve this has simply been to use the Sonos mesh.
Now I've got enough devices the mesh works across the whole home (large house is part of the reason I needed the UniFi kit in the first place!) and to set it up it's as simple as taking the existing Sonos setup (on WiFi) and plugging one of the devices into Ethernet. It then automatically creates the mesh.
For good measure I blocked them on the UniFi AP's as well so they couldn't fall back to WiFi so I'll know if the mesh setup breaks rather than it causing confusion - but I have to say it's night and day.
Previously the other half thought the Sonos was becoming a massive pain in the ass, and begrudged the app not letting her stop or start it (randomly) but now it works flawlessly and she's admitted that she likes it now!
So yeah, thought I'd post this in the off chance someone else is having similar trouble. If you're having any trouble with devices appearing on the controller, set up the Sonos Mesh by plugging one of your speakers into WiFi and don't look back.