bt_att: bt_att_recv: Unhandled ATT code 0x1b

[Dinh Son]

Hello everyone
I am using Nrf5340 Zephyr sdk v2.4.2 to broadcast BLE as a peripheral connecting 2 devices with Esp32 as central and phone at the same time, the following error occurs:
<wrn> bt_att: bt_att_recv: Unhandled ATT code 0x1b
But if I only connect to 1 Esp32 device or phone, the above error does not occur
I noticed that when connecting two devices at the same time, device 1 (Phone) will connect faster than device 2 (Esp32), is there any way to increase the connection speed

[Susheel Nuguru]

I have not seen this error before, neither did I get any hits in the internal database search. 

Can you help me reproduce this error on the DKs? Try connecting to two phones without including ESP32 so that it is easy for me to reproduce it here. Without reproducing the issue here, it is hard for me to assist you in this.

[Dinh Son]

Thanks for your feedback
I tried using Nrf5340 DK to test, when connecting to two phones at the same time, the above error did not occur. I still do not understand why when connecting toEsp32 and phone at the same time, the above error occurs

[Susheel Nuguru]

I am unsure why it is different.

Maybe you should get the air sniffer trace of the whole connection when connecting to ESP32 and compare it with the sniffer trace that you capture with the working setup with phones.