[Bug Report] Severe A/V Sync Deadlock & Audio Drop with Intel BT Driver 24.20.0.3

[Lostinspace]

This bug happened when I was using my Galaxy Book 5 pro and S25+ phone, and S9 Ultra tablet. and when autoswitch happened(or manual) from phone -> laptop or tablet -> laptop BT connection did happen but sound never cameout.

Notification: This report is made by help of the ai because I am not that good at English.

Hello, I am reporting a critical compatibility bug and bandwidth throttling issue introduced in the latest Intel Wireless Bluetooth Driver (v24.20.0.3). When using multipoint Bluetooth connections (specifically Samsung Galaxy Buds2 Pro with 'Auto Switch' feature enabled across PC, Tablet, and Phone), the v24.20.0.3 driver causes a complete audio routing failure and A/V sync deadlock on Windows 11.

System Environment:

• OS: Windows 11

• Device: Samsung Galaxy Buds2 Pro

• Trigger Condition: Samsung "Auto Switch" (Continuity Service) active across multiple devices (May related to Heavy Bluetooth LE background pinging).

Symptoms (with v24.20.0.3):

1. Audio Drop & Deadlock: Windows claims the Bluetooth device is connected, but no sound is outputted.

2. Browser Pipeline Destroyed: Chromium-based browsers (Chrome/Edge) suffer infinite buffering on YouTube. The browser's Media Internals show State: Destroyed and missing audio decoders due to the driver failing to establish an audio channel (A2DP).

3. No Windows Event Logs: Windows Event Viewer shows no crashes (BTHUSB or Audiosrv), indicating a logical bandwidth/protocol denial rather than a service crash.

Resolution / Workaround:

• Rolling back the Intel Bluetooth Driver to v23.140.0.5 completely resolves all issues.

• It appears the newer 24.x driver handles LE bandwidth or multipoint polling too aggressively, choking the audio channel when the Samsung ecosystem sends background continuity pings.

Please investigate the Bluetooth LE bandwidth management in the 24.x driver series regarding high-frequency background polling from multipoint devices.

[Goutham_intel]

Hello Lostinspace,

Thank you for posting in the community and for sharing the detailed description of the behavior. We also appreciate the effort you made documenting the steps and observations.

To better understand the configuration, could you please confirm which Intel® wireless adapter model is installed in your Samsung Galaxy Book 5 Pro? You can verify this in Device Manager → Network adapters.

Additionally, we would like to share an important note regarding the Intel® Wireless Bluetooth® driver version 24.20.0:

Important:

For systems using Intel® Wireless-AC 9560, Intel® Wireless-AC 9462, or Intel® Wireless-AC 9461, when upgrading from driver versions 23.10.x.x – 23.50.x.x to 24.20.0, it is recommended to disconnect and unpair all previously paired Bluetooth® devices before performing the driver upgrade. After the installation is complete, the devices can be paired again.

You mentioned that Windows shows the device as connected but no audio is produced, and that no Bluetooth or audio service errors appear in Event Viewer. In scenarios involving device auto-switching or multipoint connectivity across multiple devices, the behavior can depend on how the feature is implemented across the different platforms involved.

For reference, Bluetooth® LE Audio features require support from both the Windows system and the audio device. To use LE Audio on Windows, the following conditions must be met:

• The system must be running Windows 11 version 22H2 or newer
• The platform must support Bluetooth® LE Audio hardware capabilities
• The system must have LE Audio–capable drivers for both the Bluetooth radio and the audio codec

Please note that not all Windows 11 systems support LE Audio, even if Bluetooth LE is available.

Since the scenario described involves Samsung Galaxy Buds2 Pro Auto Switch functionality across a phone, tablet, and Windows system, it may also be useful to verify with the device manufacturer whether there are any specific requirements or known limitations for this feature when used with Windows systems.

Refence article:-Check if a Windows 11 device supports Bluetooth Low Energy Audio - Microsoft Support

ReleaseNotes_BT_24.20.0.3.pdf

Best regards,

Goutham

Intel Customer Support Technician

[Lostinspace]

Hi Goutham_intel,

Thank you for the detailed response and for reviewing my bug report.

As requested, here is my exact system configuration:

• Network Adapter: Intel(R) Wi-Fi 7 BE201 320MHz

• CPU: Intel Core Ultra 7 (Lunar Lake)

• OS: Windows 11 (Version 25H2)

Regarding your notes on the Intel® Wireless Bluetooth® 24.20.0 driver:

1. About the Upgrade Note: I understand the recommendation to unpair/repair devices for the older AC 9560, 9462, and 9461 adapters. However, my adapter is the modern Wi-Fi 7 BE201. Even so, I have already performed a completely clean install of the 24.20.0.3 driver (including unpairing all Bluetooth devices and clearing the Bluetooth cache). Unfortunately, the A/V deadlock and audio drop issue still persists with version 24.20.0.3.

2. About LE Audio & Samsung Auto Switch: My Lunar Lake system and the BE201 adapter fully support Windows 11 LE Audio capabilities. I agree that there could be problem with Samsung's "Auto Switch" feature so I made bug report to them as well.

3. The Core Issue (Regression): The crucial point is that this exact same hardware and OS configuration works flawlessly on the older Intel Bluetooth Driver version 23.140.0.5. The deadlock and browser pipeline failure (State: Destroyed) ONLY occur on the newer 24.x driver branch.

This strongly indicates a driver regression in how the 24.20.0 driver handles LE bandwidth throttling, multipoint polling, or LE Audio routing when flooded with background pings from the Samsung ecosystem.

Could you please escalate this specific regression behavior (v23.x vs v24.x on BE201) to the driver development team? I am more than happy to provide any advanced logs (Event Viewer, traces, etc.) if your engineering team needs them.

Thank you for your support.

[Goutham_intel]

Hello Lostinspace,

Thank you for posting on the Intel Community Forum.

Kindly note that we have requested additional details via email to further investigate the issue. Please check the inbox of your registered email address and revert at your earliest convenience.

Best regards,

Goutham

Intel Customer Support Technician

[Lostinspace]

Hi Goutham_intel

If you saw the resent reply in gamil, please respond.

[Goutham_intel]

Dear Lostinspace,

I hope you are doing well.

I wanted to follow up regarding the additional tests we requested for your Bluetooth audio issue. Once you have gathered the requested details—testing the driver with a different headset and/or testing your current headset on another device—kindly reply to the internal email so we can review the results and assist you further.

Your input will help us narrow down the root cause and provide the appropriate guidance.

Thank you for your cooperation.

Best regards,

Goutham,

Intel Customer Support Technician

[Goutham_intel]

Hello Lostinspace,

Thank you for the detailed update.

From your findings, it appears the behavior is linked to Samsung’s Auto Switch feature when waking from Sleep Mode. It’s helpful to know that Samsung has acknowledged the issue and plans to address it in an upcoming Settings app update.

We also appreciate the screenshots and details you shared earlier.

The case will remain open while you test the latest Samsung firmware and app updates. Please share your observations once you have results.

Thank you for your cooperation.

Best regards,

Goutham,

Intel Customer Support Technician

[Lostinspace]

CRITICAL Update on Case #: 06813125 - Reproduced on 3rd-Party Devices (Prolonged Sleep Bug)

Hi Goutham,

I need to correct my previous update regarding the third-party device test. I have conducted further extensive testing, and I have found the definitive root cause. The issue is much deeper and points directly to a fundamental flaw in the Intel 24.20.0.3 driver, regardless of the device brand.

1. The "Prolonged Sleep (Deep Sleep)" Trigger: My previous test with the 3rd-party speaker was flawed because the laptop was only in Sleep Mode for a short time. Last night, left the laptop in Sleep Mode (Modern Standby) overnight. Upon waking the laptop this morning, the exact same severe audio distortion and A2DP routing failure occurred with the non-Samsung speaker.

2. Not a Samsung-Specific Issue: This confirms that the bug is NOT exclusive to Samsung's ecosystem or the Auto Switch feature. The Intel 24.20.0.3 driver fundamentally fails to correctly re-establish the classic A2DP audio clock/pipeline after returning from a prolonged Modern Standby state. Which I also found that this isn't only my problem because I found this "https://community.intel.com/t5/Wireless/Intel-Wireless-Bluetooth-driver-causes-video-freeze-after-Sleep/m-p/1740947#M63653".

3. LE Audio Driver Isolation: I considered testing this with the "LE Audio" option enabled. However, I noticed that enabling LE Audio switches the driver provider to Microsoft's generic "Audio Kernel Mode Proxy Unit Device," completely bypassing the Intel A2DP stack. Which is quite not helpful to this problem.

Definitive Reproduction Steps for your Engineering Team:

1. Connect ANY Bluetooth audio device (Classic A2DP mode).

2. Put the Windows 11 laptop into Sleep Mode (Modern Standby) for an extended period (e.g., 6+ hours overnight).

3. Wake the laptop and attempt to play a YouTube video or test via MMSYS.CPL.

4. Result: Audio is heavily distorted, stuttering, or completely drops out, requiring a system reboot to fix.

Please forward these exact reproduction steps to the driver development team. The 24.x driver branch clearly has a critical memory/state recovery bug related to Modern Standby. I will be rolling back to the 23.x driver for my own system stability, but I hope this detailed debugging helps your team issue a fix in the next release.

Thank you, Lostinspace

[MikeTMK]

Hi,

Just letting you know I have also run into this issue with a fairly new machine. Two sets of headphones affected.

1. Pixelbud

2. OpenFit

Both devices produce a very loud static sound when audio is attempting to play (symptomatic of an issue with A2DP issue). 

I did the following (for each headset)

1. Windows update was fully run to confirm there are no further updates (this is for an enterprise system)

2. Unpairing, Repairing the device.

3. Computer was rebooted.

4. Unpaired and repaired the device

Rolling back the driver fixes the problem, updating the driver breaks it again.

[Goutham_intel]

Hello Lostinspace,

Thank you for sharing your update and analysis on this matter.

We are currently investigating the issue in detail to identify the cause and determine the best resolution. Please allow us some time to complete this process, and we will get back to you with an update as soon as possible.

Best regards,

Goutham

Intel Customer Support Technician

[Lostinspace]

Hi Goutham,

It has been over two weeks since your last update on March 20th. I am writing to firmly request a status update on the engineering investigation regarding the BE201 chipset and the 24.x driver branch instability. Or have you found something.

While waiting for your response, I have not been idle. I recently updated my system to the absolute latest Samsung BIOS/Firmware and performed a clean installation of the newest Intel drivers. Unfortunately, the exact same power drain and instability issues persist. > This conclusively proves that the root cause lies within the 24.x driver branch itself, not the BIOS or hardware.

I have also provided my latest SSU logs and answered all required questions through the email support channel (Case #: 06813125). However, there seems to be a significant lack of coordination between the email support team and this community forum.

Thank you,

Lostinspace

[Goutham_intel]

Hello Lostinspace,

Thank you for your patience.

Please refer to the article below for recommended wireless, audio drivers, and OS configurations to ensure a better Bluetooth experience:

https://www.intel.com/content/www/us/en/support/articles/000102702/wireless.html

To proceed further with the investigation, could you please share the current Intel® Smart Sound Technology (ISST) driver version installed on your system?

This information will help us better understand your system configuration and guide you accordingly.

We appreciate your cooperation and look forward to your response.

Goutham

Intel customer support technician

[Subhankar_Intel]

Hello Lostinspace,

I hope you are doing well.

We’re following up to check if you were able to complete the recommended steps from our previous message.

If you’re still experiencing the issue, could you please share the current version of the Intel® Smart Sound Technology (ISST) driver installed on your system?

This information will help us better understand your system configuration and assist you more effectively.

We appreciate your cooperation and look forward to your response.

Subhankar

Intel customer support technician

[Chawan_Intel]

Hello Lostinspace,

I hope you are doing well.

We are following up on our previous message regarding the Intel® Smart Sound Technology (ISST) driver version request. At this stage, we are still awaiting your update.

Kindly share the current ISST driver version installed on your system so we can proceed further with the analysis and assist you accordingly.

We appreciate your cooperation and look forward to your response.

Best regards,

Chawan

Intel Customer Support Technician

[Lostinspace]

Hello @Chawan_Intel, @Subhankar_Intel, @Goutham_intel 

Sorry to keep you waiting. It's testing period in college. So I have been quite busy.

My current ISST version is 20.42.12641.6.

I will tell you more info and more precise requirements as soon as  my exam ends.

Thanks, from Lostinspace.

[Tharun_Intel]

Hello Lostinspace,

I hope your are doing well.

Thank you for your response.

We wanted to let you know that we are actively working on your issue and are fully committed to providing you with the best possible resolution. We are currently investigating the matter and requires a little more time to ensure we address your concern thoroughly and accurately.

We appreciate your patience and understanding. Please rest assured that your case is our priority, and we will follow up with you as soon as we have an update.

Should you have any questions in the meantime, please do not hesitate to reach out to us.

Tharun

Intel Customer Support Technician.

[Chawan_Intel]

Hello Lostinspace,

I hope you are doing well.

Thank you for your patience. To further isolate the issue you are experiencing, we recommend trying the following troubleshooting steps and checking whether the same behavior persists:

1. Disable ISST driver

• Open Device Manager
• Locate the ISST driver
• Disable it and check if the issue is still observed

2.Enable ISST and test with older drivers

• Enable ISST again
• Roll back the drivers
• Install and test with Bluetooth driver version 24.10.0 Intel® Wireless Bluetooth® Drivers for Windows® 10 and Windows 11*
• Install and test with Wi-Fi driver version 24.30.1 Intel® Wireless Wi-Fi Drivers for Windows® 10 and Windows 11*

3. If the issue still persists Roll back and test with the following driver versions:

• Bluetooth driver version 24.10.0Intel® Wireless Bluetooth® Drivers for Windows® 10 and Windows 11*
• WiFi driver version 24.10.0Intel® Wireless Wi-Fi Drivers for Windows® 10 and Windows 11*

Once you have completed the above tests, kindly let us know whether the issue is still occurring. Your observations will help us proceed with further analysis and provide the appropriate next steps.

Thank you for your cooperation. I look forward to your update.

Best regards,

Chawan

Intel Customer Support Technician

[Chawan_Intel]

Hello Lostinspace,

I hope you are doing well.

I wanted to follow up regarding the troubleshooting steps shared earlier to further isolate the issue, including disabling/enabling the ISST driver and testing with the recommended Bluetooth and Wi-Fi driver versions (24.10.0 and 24.30.1).

Could you please let us know if you had the opportunity to perform these steps, and whether the issue is still being observed?

Your feedback on each test scenario will help us proceed with further analysis and determine the appropriate next steps.

As we have not yet received an update, we kindly request you to share your observations at your earliest convenience so we can continue assisting you.

Thank you for your cooperation. I look forward to your update.

Best regards,

Chawan

Intel Customer Support Technician

[Lostinspace]

Hello Chawan_Intel,

I am currently in investigation with your steps. it might take a while because I want to be extra careful.

I will let you know the result as soon as it completes. It will take less than 1 week from now.

Best regards,

Lostinspace

[Chawan_Intel]

Hello Lostinspace,

Thank you for your response.

Not an issue at all kindly take your time to complete the investigation. Please do keep us updated once it is done, and we’ll be here to assist you further.

Looking forward to your update.

Best regards,

Chawan

Intel Customer Support Technician

[Chawan_Intel]

Hi Lostinspace,

Thank you for your patience.

This is a follow up. Kindly take your time to complete the investigation. Please keep us updated once it is done, so that we can proceed ahead accordingly and continue assisting you further.

Looking forward to your update.