Error 22 (0x16): GATT_CONN_TERMINATE_LOCAL_HOST only on Samsung XCover device

Question

When I run the BLE peripheral HRS example on the eval board and try to connect with a Samsung XCover3 using the "nRF Connect" app, I got the error 22 (0x16): GATT_CONN_TERMINATE_LOCAL_HOST . 
 Doing the same with a Sony Xperia ZL, I got no error. After looking in the logs, there are some interesting services discovered by the Samsung device, that are not realy advertised by the eval board. 
 My question is now, where comes the error from? Bluetooth chipset of Samsung or a bug in the softdevice? What can I do, to fix this problem? 
 
 nRF52832 
 SDK 12.2.0 
 Softdevice S132 
 Eval board PCA10040 
 
 Working device: 
 
 Device name: Xperia ZL 
 Android version: 6.0.1 
 Manufacturer: Sony 
 Model: XPeria ZL 
 Build version: cm_odin-userdebug 6.0.1 MOB31K 05f414329b test-keys 
 Board: MSM8960 
 Product: C6503 
 
 log_sony_xperia_zl.txt 
 Non working device: 
 
 Device name: Samsung SM-G389F 
 Android version: 6.0.1 
 Manufacturer: Samsung 
 Model: SM-G389F 
 Build version: MMB29K.G389FXX U1APK1 
 Board: universal3475 
 Product: xcover3veltexx 
 
 log_samsung_xcover3.txt 
 Wireshark trace with Sony XPeria ZL connecting to HRM example:
 nordic_hrm_sony_xperia_zl.pcapng 
 Wireshark trace with Samsung XCover 3 connecting to HRM example:
 nordic_hrm_samsung_xcover_3.pcapng

Sigurd · Accepted Answer

The sniffer is not up-to-date with the newest LL packets, so the name of the newest packets are shown as unknown in the sniffer. The first “unknown” packet has opcode 0x14, if you look at the Bluetooth Specifications (Core version 4.2 or 5.0) this is a LL_LENGTH_REQ packet send from the nRF52 to the Xcover, in order to enable Data length extension (DLE)/ longer on-air data packets. According to the specifications, if the Xcover supported DLE, it should have responded with a LL_LENGTH_RSP packet, and if Xcover didn’t support DLE it should have sent a LL_UNKNOWN_RSP packet. None of these packets are sent by the Xcover. 
 I suggest to use the default payload size of 27, so that the DLE procedure is not initiated ( LL_LENGTH_REQ will not be sent). Call this function before you start advertising: 
 void data_len_ext_set(void)
{
 ret_code_t err_code;
 ble_opt_t opt;

 memset(&opt, 0x00, sizeof(opt));

 opt.gap_opt.ext_len.rxtx_max_pdu_payload_size = 0;

 err_code = sd_ble_opt_set(BLE_GAP_OPT_EXT_LEN, &opt);
 APP_ERROR_CHECK(err_code);
}