I’m not sure if the problem is from a Sonos or Ubiquiti update but when I first setup my large 27 speaker Sonos system last August everything worked good. Recently I noticed that I could not group certain speakers together and I could not create a stereo pair no matter how hard I tried. The speakers would work individually fine while the grouping functions between certain speakers would fail consistently.
From long wisdom in working with large Sonos environments (I have two) I learned that in order to get the best performance and reliability I would make sure there was always at least one wired Sonos speaker in close range to every Sonos wireless only speaker to make SonosNet work best. In the end I had six Ethernet wired speakers doing this job. To accomplish this I had one wired speaker right where my main internet switch was located. I then utilized Actiontec MoCa adapters via existing coax cable to connect two more wired speakers and I also utilized the 5GHZ wireless uplink feature of the Unifi network to connect three more wired speakers. Each of these extended locations had a Unifi switch that supported spanning tree (STP) protocol correctly.
With a bit of troubleshooting I finally tracked it down this issue to a problem with the Ubiquiti wireless uplinks. It appears that something to do with multicast network traffic not correctly passing through the wireless uplinks. I found little information on the Internet about this problem. Nothing specifically about Ubiqutii and Sonos. In the Ubiquiti community this multicast/wireless uplink problem also seems to affect Apple Bonjour/MDNS device discovery and also certain IoT home automation solutions. I suspect this issue started with a Sonos update related to multicast support but that level of technical detail seems seldom shared by Sonos.
I don’t want to spend endless time trying to track this down this obscure issue and will most likely take the wireless uplinks out of the picture by deploying some Comtrend PG-9182PT powerline adapters instead unless someone has an idea?