After dozens of annoying trial and error sessions (with mostly errors :) I want to briefly share what finally worked.

Long ago the issues arose when installing my new ZenWiFi AX XT8 mesh system, when the Sonos system wouldn’t connect at all to the system. By trouble shooting turning things like the QoS off etc, I got it to work fairly stable. Until a recent FW update (3.0.0.4.388_24688) when the issue began with intermittent audio dropouts from my two Play:3 speakers, which are used as surround sound speakers in my Sonos system alongside the Sonos Arc (connected by network cable) and Sonos Sub (Gen 3). Both Play:3 speakers would simultaneously cut out for one or two seconds before resuming playback, and this happened ever 5-10 seconds. Needless to say, VERY annoying. Despite having the Arc connected via LAN cable, the Play:3 speakers continued to experience dropouts, which disrupted my overall audio experience.

Steps That Didn’t Resolve the Problem:

1. Disabling Airtime Fairness and QoS:

   • Double checked the Airtime Fairness and Quality of Service (QoS) settings were disabled - check. 
      

2. Binding Sonos Devices to a Specific Mesh Node:

   • Tried this - did not stop the audio dropouts​

What Finally Worked:

After trying several things with no success, I finally found the solution by enabling Multicast Routing in my Asus XT8 Mesh System under the LAN > IPTV settings. Once I enabled Multicast Routing, the Play:3 speakers stopped cutting out, and the issue with intermittent audio dropouts was resolved.

Multicast Routing helps by ensuring that the data streams between devices are handled more efficiently, which is crucial for systems like Sonos that rely on constant, synchronized communication between speakers. After this adjustment, my Sonos system has been working flawlessly.