I'm seeing the same thing in the released version of iOS16. In Segger Studio debug console the event is : app_ble: BLE_GAP_EVT_DISCONNECTED event received. It then reconnects right away with : app_ble: BLE_GAP_EVT_CONNECTED event received. It runs for a couple minutes, and then disconnects and reconnects. I'm running on our BT Sensor using an nRF52833 with the latest Nordic SDK nRF5 SDK 17.0 I've tried turning off and on BT, restarting the iPhone, this seems to help, but it still occurs.

So another post on this iOS16 issue. It appears Apple changed the Bluetooth Development guidelines so Minimum and Maximum connection intervals are now Min 15 ms, and Max 30 ms. This is defined in Nordic SDK in app_ble.c you need to change your parameters to this now: /* Minimum acceptable connection interval (20ms). Force the connection interval to be 15ms to maximize throughput. iOS devices will not handle a faster interval. Refer to the Apple Bluetooth development guidelines for further details. / #define MIN_CONN_INTERVAL MSEC_TO_UNITS(15U, UNIT_1_25_MS) / Maximum acceptable connection interval (30ms). */ #define MAX_CONN_INTERVAL MSEC_TO_UNITS(30U, UNIT_1_25_MS)