Google Cast app finds no devices; all 5 Cast devices went "unavailable", then vanished after a Homey restart (Homey Pro Early 2023)

Questions & Help
1

Setup

  • Homey Pro (Early 2023), firmware 13.5.0
  • Google Cast app [version after reinstall, previously 6.1.5], Google TTS app v2.1.0
  • Cast devices on my network: Chromecast Audio, Nest Audio, Google Home Mini, Lenovo Smart Display (plus a Cast group), and a Google Home speaker
  • UniFi Dream Machine network, everything on one flat subnet (no VLANs, no client isolation)

What happened

  1. All 5 of my Cast devices in Homey showed “This device is currently unavailable”, while the speakers themselves were working fine in the Google Home app.
  2. I restarted the Google Cast app three times. No change.
  3. I did a full Homey restart. No change for the Cast devices.
  4. I removed the Google Cast app and installed it again from the app store. Adding a device via Devices → + → Google Cast still finds nothing, including a Google Home speaker that had never been added to Homey.

What I’ve ruled out

  • Network path is fine. From another computer on the same LAN, all the Google devices answer mDNS (_googlecast._tcp) and accept connections on TCP 8009.
  • Not a Wi-Fi band or SSID issue. Homey was on a 2.4 GHz SSID and the speakers on a 5 GHz SSID, so I moved one speaker onto the same SSID, access point and channel as the Homey. Still not found.
  • Not multicast enhancement. I turned it off on Homey’s SSID. No change.

Questions

  1. Is there a known issue with the Google Cast app on Homey firmware 13.5.0?
  2. Can the app’s logs be viewed anywhere? I can’t find them through the API.
  3. Is there a way to force a fresh mDNS/Cast discovery on Homey, or to check what Homey’s discovery is actually seeing?

Thanks!

2

Embarrassed i didnt find this sooner… Update in case this helps someone else. The cause was a UniFi Wi-Fi setting, not Homey or the Cast app.

Cause: the Wi-Fi network Homey was connected to had “Multicast and Broadcast Filtering” turned on (in newer UniFi versions it’s worded like “Block LAN to WLAN Multicast and Broadcast Data”). That setting stops multicast traffic from
reaching Wi-Fi clients. Google Cast devices announce themselves over mDNS, which is multicast, so their replies never reached Homey. Homey could send its query, but it never got an answer, so the Cast app found nothing.

How I found it

  • A computer on the same network (wired) could see every Cast device and connect to it, so the network itself was fine.
  • Homey and the speakers were on different Wi-Fi networks. Comparing the settings of the two networks showed the multicast filter was only enabled on Homey’s network.

Fix: in UniFi, go to Settings → WiFi → [the network Homey uses] → Advanced, and turn off the multicast and broadcast filter. Then restart the Google Cast app (or reinstall it) and add the devices again. After turning it off, Homey’s
own discovery immediately listed 11 Cast devices, which it hadn’t been able to see before.

Things that did not help (so you can skip them): restarting the Cast app, a full Homey restart, moving a speaker onto the same SSID, access point and channel, and turning off “multicast enhancement” (a different setting).