Some more updates on this topic. Since end of September, there is a case open at Apple about this issue. The problem also appears on HomePods 2nd generation which are not in a stereo pair.
Support from the case tries to help and wants to pull some extended diagnostics from the HomePods when the issue happens. Unfortunately, you cannot pull this data by yourself. This needs to be done by the support with the help of a rolled out profile on your iPhone, or iPad, exactly at the moment the issue appears. As you might already can image, hard to hit exactly the time the issue appears and having the support on the phone.
But here some background information about the WiFi environment and strange behaviour I see from the HomePods:
- I'm using network equipment from Ubiquiti: 1x UDM SE (SW: 4.0.21), 2x U6 Pro (6.6.77) and 1x U6 Plus (6.6.78)
- 5GHz + 2.4GHz Wifi with automatic channel and transmit power selection
- All APs serving 3 WiFi SSIDs
- All Apple devices are in the same Wifi SSID
- All HomePods are spread across the 3 APs.
- Mesh has been turned off system wide
- mDNS is turned on for 2 VLANs (Apple devices, HomeKit and Matter are in the same VLAN, some other smart home stuff is located in a different VLAN)
- Multicast enhancement and IGMP snooping is turned of, because it disturbs Thread device communication
- Band Steering and BSS transition is turned on for all Wifi SSIDs (all APs have the setting to Prefer 5GHz)
- Security Protocol is WPAs/WP3
- For 2.4GHz the Wifi channel width is 20MHz
- For 5GHz the Wifi channel width is 40MHz
I used Ubiquities Wifiman App to validate the RSSI and it was looking good. The HomePods usually having between -42dBm and -65dBm (depending on which AP they are using).
When the stereo pair starts to make the distorted sounds, they usually also start to generate a playback delay between each other and getting completely out of sync.
All of the time the HomePods (2nd Gen and also Minis) using the 5GHz Wifi, but very often they are using 20MHz channel width, instead of the offered 40MHz. From what experienced, the problems usually started to happen in such situations. If they are using 40MHz channel width, as offered by the APs, then I could not experience the issue. I'm not yet 100% sure about it, because I cannot force the HomePods to use the 40MHz.
If someone has a similar setup and no issues, or had similar issues in the past and was able to solve it, I'm happy to get any feedback, or suggestions.
Thanks in advance for your constructive reply.
