I’ve been reading a lot of information here, on Reddit, on Synology’s site (my router is Synology), and on Apple’s communities. I’ve also done many web searches and AI chats. Finally, I chatted with Sonos support and talked by phone (lots of time spent). The Sonos support included sending diagnostics a few minutes after the problem on three different occasions. Most recently, I did some digging with the help of Airplay documentation and searches. What I’ve found is that my Arc Ultra and Era 300s do not appear to be advertising AirPlay via mDNS correctly. My Sonos Amp is working fine. Here are technical details:
Summary
My Sonos Arc Ultra ("Bedroom") is advertising its AirPlay service via mDNS, but it consistently uses flags=0x4 instead of the expected 0x804. This prevents it from appearing as an AirPlay target on iOS/macOS devices, despite being on the same network and access point.
Network Setup
- Router: Synology RT6600ax (SRM 1.3.1)
- Mesh: Synology mesh nodes, multicast forwarding enabled (also tried with this disabled)
- Wi-Fi: Devices tested on same 2.4 GHz SSID and access point
- IPv6: Disabled
- AP Isolation: Disabled
- IGMP Snooping: Enabled
- Static IPs: Assigned to all devices
Devices
- Working Sonos Amp: “Media Room (2)” — shows flags=0x804 in mDNS
- Non-working Arc Ultra and Era 300s: “Bedroom” — show flags=0x4
Diagnostic Output
`dns-sd -B _airplay._tcp`
14:29:34.676 Add 3 17 local. _airplay._tcp. Media Room (2)
14:29:34.677 Add 3 17 local. _airplay._tcp. Bedroom
`dns-sd -L "Bedroom" _airplay._tcp`
Bedroom._airplay._tcp.local. can be reached at Sonos-C438751F3C4E.local.:7000 (interface 17)
flags=0x4 model=Arc Ultra manufacturer=Sonos fv=p20.91.0-70070
What I’ve Tried
- Rebooted speaker, router, and devices I’m air playing from
- Ungrouped speaker in Sonos app
- Verified firmware is current (p20.91.0-70070)
- Confirmed no duplicate hostnames or MAC conflicts
- Tested with iPhone and Sonos on same AP and band
- Verified mDNS visibility across interfaces
Request
It appears that the Arc Ultra and Era 300s are broadcasting incorrect AirPlay capability (0x4) rather than the expected capability (0x804). Since I’ve not found anything on my network interfering with these speakers’ broadcasts and the Amp is broadcasting correctly, is there a known issue with mDNS advertisement on Arc Ultra or firmware p20.91.0-70070 that could cause this?
Thank you.
