Galaxy Tab A8 fails to connect properly, while Galaxy Phone S10 works fine

[tellg]

Galaxy Tab A8 connects, but then disconnects after a burst of approx 600 "Central_0x2a208f55 Peripheral_0x2a208f55 ATT 37 Sent Read By Group Type Request, Primary Service, Handles: 0x0001..0xffff"

Galaxy S10 works fine

Bot are running the same mobile app.

I have attached 2 Wireshark capture files, one for Samsung Galaxy Tab A8, the other for Samsung Galaxy S10 

We use ncs 2.6.1 on our nRF52840 hardware

SamsungS10.pcapngsamsungA8.pcapng

[Simonr]

Hi

In 2022, we found an issue in the Samsung A8 series Bluetooth capabilities, where it apparently tries to send packets with longer payloads than what has been negotiated, which caused these issues to occur. It has been reported to Samsung, but I do not have a status beyond that I'm afraid. There is nothing to be done from the nRF side of the application to remedy this I'm afraid.

Best regards,

Simon

[tellg]

We have seen that it helps setting  CONFIG_BT_AUTO_PHY_UPDATE=n on the peripheral, and setting client side mcumgr initial mtu setting to 23

ref https://github.com/search?q=repo%3ANordicSemiconductor%2FAndroid-nRF-Connect-Device-Manager%20initialmtu&type=code 

Downside is that devices already out in the field have CONFIG_BT_AUTO_PHY_UPDATE as default, which is 'y'

Is it possible from mcumgr android library to force using 1 Mbit phy when the device is SM-X200 (Galaxy tab A8)?

If so, then maybe also do this in the other libraries for SM-X200 (https://github.com/NordicSemiconductor/Android-BLE-Library and https://github.com/NordicSemiconductor/Android-DFU-Library)