Repeated connection interval updates on iOS 26

RE: Repeated connection interval updates on iOS 26

HarryGe — Fri, 17 Oct 2025 08:38:40 GMT

Are you using the Bluetooth MIDI service? I found that as long as I turn off this service, the system will be normal.

RE: Repeated connection interval updates on iOS 26

HarryGe — Tue, 14 Oct 2025 08:47:43 GMT

Of course I'll report this issue.
I also found that this problem may be related to the HID service. After I commented out the HID service, although it still triggered repeated updates, the connection parameters became normal and the triggering frequency was much lower.

RE: Repeated connection interval updates on iOS 26

nrbrook — Tue, 14 Oct 2025 08:26:26 GMT

I haven't solved the problem, my bug report with Apple is still open. Please report too, the more reports the faster they respond: feedbackassistant.apple.com/

RE: Repeated connection interval updates on iOS 26

HarryGe — Tue, 14 Oct 2025 07:59:43 GMT

Hello nrbrook,
I have the same problem, iOS 26 keeps sending me connection parameter updates until I get an error saying Reason: 0x28 disconnected.
Then it automatically reconnects and disconnects again in a loop.
I'd like to know how you solved this problem, thank you very much.

RE: Repeated connection interval updates on iOS 26

Amanda Hsieh — Thu, 18 Sep 2025 15:13:16 GMT

[quote user="nrbrook"]This doesn't happen in previous iOS versions[/quote]

Please contact the Apple support team for help.

RE: Repeated connection interval updates on iOS 26

nrbrook — Thu, 18 Sep 2025 11:13:29 GMT

Yes it does. Apple's guidelines from developer.apple.com/.../Accessory-Design-Guidelines.pdf

General connection parameter request guidelines:
● Peripheral Latency ≤ 30 connection intervals.
● Supervision Timeout from 6 seconds to 18 seconds.
● Interval Min ≥ 15 ms.
● Interval Min ≤ 2 seconds.
● Interval Min is a multiple of 15 ms.
● One of the following:
● Interval Max at least 15 ms greater than Interval Min.
● Interval Max and Interval Min are both 15 ms.
● Interval Max * (Peripheral Latency + 1) of 6 seconds or less.
● Supervision Timeout greater than Interval Max * (Peripheral Latency + 1) * 3.
If Bluetooth Low Energy HID is one of the connected services of an accessory, a connection interval
down to 11.25 ms may be accepted by some devices.
Note:
When Interval Max and Interval Min are both 15 ms, some devices (such as Apple Watch) will
offer a 30 ms interval to better balance power and performance constraints.

As mentioned, I tried using a variety of intervals, all have the same issue. I've checked all calls to sd_ble_gap_conn_param_update, we aren't calling it repeatedly, and also the packet trace shows all updates are coming from iOS side. This doesn't happen in previous iOS versions

RE: Repeated connection interval updates on iOS 26

Turbo J — Thu, 18 Sep 2025 11:09:22 GMT

Does your device expose HID service?

Those get different connection intervals on iOS, and may cause the central to switch to low latency connection parameters. I believe this is documented by apple somewhere.