BLE pairing fails on the new NRF54L15DK

[maverick11]

Describe the bug

BLE pairing on the new NRF54L15DK does not succeed. Connecting and advertising works, only pairing fails. I have tried the same example on the NRF52840DK and it works. Also tried pairing using Android and iOS (Samsung and Iphone 16), same result is achieved.

To Reproduce

1. Flash the Bluetooth fundamentals lesson 5 - exercise 1 example or any BLE pairing example (academy.nordicsemi.com/.../)
2. Try to pair to the device
3. See that it won't pair

Expected behavior

Should pair with the device as it does on the nrf52840dk.

Logs and console output

[00:00:00.433,931] Lesson5_Exercise1: Advertising successfully started

[00:00:19.862,201] Lesson5_Exercise1: Connected

[00:00:19.862,282] net_buf: Timeout discarded. No blocking in syswq
...
[00:00:54.337,414] bt_smp: SMP Timeout
[00:00:54.337,435] bt_smp: The in-progress pairing has been deleted!
[00:00:54.337,490] Lesson5_Exercise1: Security failed: XX:XX:XX:XX:XX:XX (random) level 1 err 9

[00:00:57.428,238] Lesson5_Exercise1: Disconnected (reason 19)

Environment (please complete the following information):

• OS: Linux - Manjaro
• Vanilla Zephyr
• v4.0-branch

[Kenneth]

Hi,

The nRF Connect SDK is built on top of Zephyr RTOS, but includes additional features and optimizations specifically for Nordic. While vanilla Zephyr can be used with Nordic hardware, the nRF Connect SDK is recommended for Nordic device development as it provides optimized support and additional features specific to Nordic's ecosystem, such as the softdevice controller for BLE.

If you experience issues with vanilla zephyr (and not nRF Connect SDK), then please contact the zephyr community for support.

Kenneth