I have a Unifi setup, and have all IoT devices (including Sonos) on a separate VLAN to my main computers and phones. This has always worked well, using an IGMP proxy and mDNS reflector, setup on the Unifi Security Gateway.
All of a sudden, this has stopped working, and not just for me. Consensus on reddit seems to be this is due to the latest Sonos firmware update: https://www.reddit.com/r/UNIFI/comments/e1dpl6/sonos_igmp_proxy_suddenly_broken/
Manually connecting the iOS device to the VLAN with the Sonos devices, and opening up the Sonos app connects. You can then go back to the normal VLAN on the iOS device and the app continues to work no problem. However, kill the app, and try to reconnect to Sonos when the iOS device is connected to the main network, and it can’t find any Sonos devices. It’s that initial connection/discovery bit that is broken, even when the app has previously been connected to the devices.
Is anyone else seeing this, and are Sonos aware?