Setup is: 2x Era300 configured as a stereo pair + Sub Gen 3.
Music is played from a desktop computer to the Era 300 via Bluetooth.
Because the desktop frequently connects and disconnects from the system, the Sub randomly stops producing audio during Bluetooth playback.
Once the issue occurs, the Sub does not recover on its own. Audio output from the Sub remains absent indefinitely until some form of reinitialization is performed (for example, reconnecting Bluetooth or power-cycling the Sub). I have never observed the Sub resume playback by itself after the issue has occurred.
Observations:
The room remains correctly bonded in the Sonos app.
Sonos app playback works normally, and the Sub works normally when using Sonos native playback.
However, after using Sonos app playback and then switching back to Bluetooth playback from the desktop, the Sub does not start working again. It remains absent from the Bluetooth source.
The issue appears to occur only during Bluetooth playback.
Disconnecting and reconnecting Bluetooth using the physical Bluetooth button on the Era sometimes restores Sub output, but not always.
Power-cycling the Sub restores operation.
Bluetooth playback may use a different audio routing path than Sonos native playback. The Era 300 pair may still behave as if the Sub is bonded and active, but the Sub stops receiving or playing the Bluetooth-routed low-frequency signal.
An additional observation supports this theory. When the issue occurs, the Era 300 speakers do not appear to switch back to their normal full range response. I am very familiar with how the stereo pair sounds with the Sub disabled. In that case, the Era 300 speakers immediately take over the bass duties and only the deepest frequencies are missing. During this issue, however, a much larger portion of the bass range is missing, suggesting that the crossover remains active and the system still believes the Sub is present and playing, even though no bass is actually coming from the Sub.
I also own a Sub 4, currently paired with an Arc, but I have not yet tested using the Sub 4 instead of the Sub 3 to see whether the same issue occurs with that setup.
I am still testing different ways to restore Sub output when the issue occurs, to determine which reset method is the simplest and most reliable.
New test: while the issue was present with desktop Bluetooth playback, I connected a phone via Bluetooth and played audio. The Sub worked immediately without power cycling the Sub. After switching back to the desktop and reconnecting Bluetooth, the Sub also started working again.
