https://devzone.nordicsemi.com/f/nordic-q-a/30015/connection-quick-disconnect-error-code-ble_hci_conn_failed_to_be_establishedHi All: I met a trouble， i don&#39;t slove it. i need help . sdk : nRF5_SDK_14.0.0 S132 hardware: nrf52832 base multitole dev. nrf52832 as master to connect mobile by ble. but the connection is always easy to to disconnect. error code is BLE_HCI_CONN_FAILED_TO_BE_ESTABLISHEDen-USTelligent Community 13Tue, 06 Feb 2018 09:25:24 GMThttps://devzone.nordicsemi.com/thread/119889?ContentTypeID=1Tue, 06 Feb 2018 09:25:24 GMT137ad170-7792-4731-bb38-c0d22fbe4515:765982c7-61e2-423e-85e0-6979390fe29frun_ar<p>Which softdevice revision are you using? And what phone are you connecting with?</p> <p>The connection parameter does not matter. Looks like it is the connection request itself that is failing.</p> <p>Anyway using 10 as connction supervision timeout might be a bit low. If it works with your use case I would at least double that.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/119284?ContentTypeID=1Wed, 31 Jan 2018 01:56:24 GMT137ad170-7792-4731-bb38-c0d22fbe4515:bd7aa971-e9ee-40c8-99bd-b301ad2c6f21Not2Good Sir<p>Hi run_ar: Thanks for your reply. this occationaly happen. about 20%, i guess this maybe related to the connection parameters. What connection parameters on the use of connection any reference ? i use 7 7 0 10 now.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/119283?ContentTypeID=1Tue, 30 Jan 2018 14:04:15 GMT137ad170-7792-4731-bb38-c0d22fbe4515:166de37c-9d9e-407a-8b96-dd01227dea8crun_ar<p>Does this happen all the time or only occationaly? If it happens occationally I doubt there is anything you can do about it. I.e. if there are any issues with the connection request you will not be able to establish a connection. If it happens always, you need to check that you are not using a whitelist with another device in it.</p><div style="clear:both;"></div>