High Failure Rate in START ENCRYPTION Sequence: 2 Failures per 10 Trials (Baseband or Link Layer Issue)

[Charles Changhun Han]

Hello Nordic Semiconductor tech support team,

HW : nRF52840 ( Build code : nRF52840-CKAA-F )

SW : ncs 2.6.0

Sample Application :  zephyr/samples/bluetooth/hci_spi sample with SoftDevice Controller

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While verifying our software design, we frequently encounter connection errors. Could you help us identify the possible cause of this issue and suggest a resolution? Right after the enhanced connection is completed, we’re expecting an Encryption Change Event from the SoftDevice Controller. However, instead of an Encryption Change Event, a Disconnect Complete (0x05) occurs with the reason ‘Connection Terminated due to MIC Failure (0x3d).

Device A : Android Mobile Phone (central), (iOS case is also reported)

Device B: nRF52840 (Peripheral) 

Frame 17605: 7 bytes on wire (56 bits), 7 bytes captured (56 bits) on interface Fake IF, Import from Hex Dump, id 0 (inbound)
Bluetooth
Bluetooth HCI H4
Bluetooth HCI Event - Disconnect Complete
Event Code: Disconnect Complete (0x05)
Parameter Total Length: 4
Status: Success (0x00)
Connection Handle: 0x00cd
Reason: Connection Terminated due to MIC Failure (0x3d)

(highlighted marked HCI events)

[Charles Changhun Han]

Subject: Request for Detailed Information on DRGN-23204

Hi Kenneth,

According to our local AE, NCS v2.8 was frozen on October 3rd. However, I am still unable to find DRGN-23204 in the changelog of the main branch. When the information for DRGN-23204 is published, could we receive more detailed information?

We are observing this issue with iOS 14 as well. If the SoftDevice controller includes a fix, I would like to have more details to close our open quality tickets.

Thank you for your assistance.

Best regards,

Charles