BLE audio packet loss on iPhone 17 (Bluetooth 6 / N1) in real-time streaming

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Hello Apple Bluetooth team,

We are developing a real-time call translation system that streams raw PCM audio over BLE between iPhone and custom earbuds.

This works reliably on iPhone 14 / 15 / 16, but on iPhone 17 (Bluetooth 6, N1 chip) we see severe and repeatable BLE packet loss, affecting both microphone uplink and TTS downlink.

Our audio stream

16 kHz, 16-bit mono PCM

20 ms frames (~640 bytes)

continuous bidirectional BLE streaming

What happens on iPhone 17

BLE packets are frequently dropped

entire audio frames are missing

results in ASR gaps and broken TTS playback

occurs even with strong RSSI and no RF interference

Same firmware, same BLE protocol, same MTU and connection interval work normally on older iPhones.

Questions

We would like to know:

Did Bluetooth 6 / N1 change BLE throughput, buffering, or scheduling?

Are there new limits on sustained notify / write-without-response traffic?

Is BLE audio now arbitrated differently against Wi-Fi / A2DP on iPhone 17?

Is BLE still expected to support low-latency continuous audio streaming on iPhone 17, or is this no longer a safe assumption?

Any guidance or new best practices would be greatly appreciated.

Best regards, Valenti Zhang

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Answer 1

Engineer OP

Apple

22m

We would need to see some logs to understand what might be happening. While this could be due to a change in the chipset, we also see that sometimes accessories making assumptions about timing of events and commands, which are bound to change over time, especially with new devices and new chipsets.

Nevertheless, a bug report with detailed logging is the way to go for this.

First we need a Bluetooth diagnostic logs.

Please go to https://developer.apple.com/bug-reporting/profiles-and-logs/ and follow the instructions for Bluetooth for iOS to install a logging profile on your device.

Then, once the logging profile is installed:

reproduce the problem, keeping track of the actual time of the actions you take and the result you see.
also include a sniffer log of the same. Please include the actual log, and an ASCII export of it from the logger.
make sure there aren’t any extraneous BLE devices around, and no other apps are trying to connect to some other BLE device while you are conducting this test.

Once the problem is reproduced, follow the instructions at the above link to trigger a sysdiagnose

If you can repeat the same on a different device where things work without an issue, that would be helpful as well. Please include logs from that test too.

Please also indicate the BLE hardware you are using, along with hardware and firmware version info, and the SDK info for the chipset.

Then, please create a bug report at https://feedbackassistant.apple.com/ and include all logs and relevant details.

Once you have done so, please post the Feedback ID here, and @mention me in your response so we can promptly route the bug to the correct team.

Argun Tekant /  WWDR Engineering / Core Technologies

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