https://devzone.nordicsemi.com/f/nordic-q-a/60933/long-duration-of-1-5sec-to-establish-a-connection-with-ble5-on-nrf52840Hi, we have two nrf52840 which shall connect very quickly. The scan+advertise cycle is very fast (we have no bootloader). After switching on the peripheral it is recognized by the central in probably 0.1sec But the connection cycle takes about 1en-USTelligent Community 13Mon, 04 May 2020 08:54:14 GMThttps://devzone.nordicsemi.com/thread/247789?ContentTypeID=1Mon, 04 May 2020 08:54:14 GMT137ad170-7792-4731-bb38-c0d22fbe4515:cc631612-d6a7-42b7-8f3e-db5f361f97e3haakonsh<p>The connection is usually established very fast, what takes time is the Service Discovery procedure. In the Service discovery procedure, there are about 10-20 messages sent back and forth to iterate trough the ATTribute table of the Peripheral. If the connection interval is 100ms you will have a delay of 1-2s before the central can enable any notifications or read any characteristics. Lowering the Connection interval will reduce this delay, you can increase the connection interval to 100ms afterward if that&#39;s your goal.&nbsp;</p> <p>I suggest you set up a DK as a sniffer according to&nbsp;<a title="nRF Sniffer for Bluetooth LE" href="https://infocenter.nordicsemi.com/topic/ug_sniffer_ble/UG/sniffer_ble/intro.html?cp=8_4">RF Sniffer for Bluetooth LE</a>, and study the sniffer trace of one of your connection establishment events. This will give you a good insight into what&#39;s going on on-air.&nbsp;</p><div style="clear:both;"></div>