I have a brand new Microsoft Surface Pro 9 with Windows 11. I plugged in my old 3.5mm headphones via the external monitor connected through a Surface dock (the monitor itself does not have sound, just a microphone jack) and Widows detected them, installed the correct driver (N32QW-DP HD Audio Driver for Display Audio) and audio played successfully for about 10 seconds, then just stopped. Unplugging and re-plugging the 3.5mm cable occasionally resulted in the audio device returning to the list and sound working again. Sometimes it would run for several minutes then just stop again.
I thought maybe the problem was running headphones through a monitor or a faulty cable/plug, so I purchased brand new JBL TUNE520BT Bluetooth headphones. When I turned them on, the Surface Pro detected them and installed the latest driver "Headphones (JBL TUNE520BT)". These worked fine for about a minute, then the audio just stopped again. Waiting a while (several minutes), the driver re-appeared in the list of connected devices, and audio commenced again for a while. After some testing, it appeared that the audio stopped at around the same time every time during a You-Tube video. It was like there was something "triggered" within the audio driver that disconnected the headphones (e.g. something else trying to use the audio output device), then reconnected them again. Almost like a pop-up ad starting up taking control of the selected audio device. This time the anomaly was accompanied with a message on the headphones "power on, connected", which indicates that the connection was momentarily interrupted and restored.
I have tried different 3.5mm headphones, same problem. All these headphones work fine on other devices and my older Surface Pro at work, which has the same setup but is running Windows 10 and has its own 3.5mm jack.
I therefore don't think the issue is specifically Bluetooth or headphone-related. The same problem happens with the hardwired headphones via the external monitor. It appears to be a problem with the Windows 11 audio management system, which for some reason is choosing to "lose" any audio device other than the built-in audio device "Speakers (Realtek High Definition Audio(SST))". When I play audio through these built-in speakers the problem does not occur - sound continues without interruption. However, I don't want the sound to come out through speakers, I want it to come out through headphones for privacy.
I have already:
* Disconnected and reconnected the drivers and devices
* Installed Windows 11 from scratch
* Installed the latest hardware drivers for all devices
* Un-selected "Allow applications to take exclusive control of this device"
* Taken the tablet far away from any potential EMI interference sources (and Bluetooth headphones were within a metre of the tablet).
Windows spec:
Edition Windows 11 Home
Version 22H2
Installed on 28/08/2023
OS build 2**********
Serial number 0F**********
Experience Windows Feature Experience Pack 1**********
***Moved from Windows / Windows 11 / Devices and drivers***