Samsung Galaxy A51 connection problem

[Sven Krauss]

Hi Matthias,

I've a problem with Samsung Galaxy A51 and the btstack. The btstack (with an CC2564C) works fine with most Smarthones. But the A51 has connection problems. In 90 percent the connection fails. I'm using LightBlue for the testing. 

I setup a ble sniffer with the nRF52840 dongle and captured the event. The interesting packages starting from no 1776.

You can load the wireshark file from here:

https://nextcloud.esk.digital/s/4jJ5QEAHJAqsiXi

It's interesting that the A1 tries to read the handle 0x0001 which is the GAP service and the btstack respons is an "attribute not found error". I'm not sure if thi is the root cause due to the fakt, that the connections is established sometimes.

Can you please check it? 

Kind regards

Sven

[Sven Krauss]

Update!

It seems that the connection parameter update causes the issue. I'm calling gap_request_connection_parameter_update() directly after the HCI_SUBEVENT_LE_CONNECTION_COMPLETE event.
If I disable the connection parameter update, everything works fine.
My assumption is that doing the update directly after the connection complete event interferes with the discovery process on the smartphone. I guess this causes packet loss or something else.
What's the recommended way to request faster connection parameters?