https://devzone.nordicsemi.com/f/nordic-q-a/124427/nrf5340---move-from-ble-security-level-4-to-level-2Our peripheral medical product, based on the nRF5340, is designed to pair and bond with both PC and mobile devices via Bluetooth Low Energy (BLE). I&#39;ve implemented BLE Security Mode 1, Level 4 (LE Secure Connections with MITM protection and encryptionen-USTelligent Community 13Wed, 17 Sep 2025 16:35:46 GMThttps://devzone.nordicsemi.com/thread/549080?ContentTypeID=1Wed, 17 Sep 2025 16:35:46 GMT137ad170-7792-4731-bb38-c0d22fbe4515:0a7b2c43-38a4-4506-b735-76d867a5def9Amanda Hsieh<p>Hi,&nbsp;</p> [quote user=""]Based on your expertise, is this a valid concern?[/quote] <p><span>Yes, it&#39;s valid.&nbsp;</span>Security Level 4 (LESC) requires<span>&nbsp;both devices to support LESC and handle passkeys. If either device does not support these features, the connection will fail to reach Level 4 and may be terminated. E</span><span>specially older mobile devices may not support the necessary authentication methods or LESC at all.&nbsp;If your application does not require the highest level of security, using Level 2 is often sufficient and more broadly supported.</span></p> [quote user=""]In the settings listed above, what to change to downgrade from Level 4 to Level 2?[/quote] <p>Revert the steps from Level 2 to Level 4 in this tutorial&nbsp;<a href="https://academy.nordicsemi.com/courses/bluetooth-low-energy-fundamentals/lessons/lesson-5-bluetooth-le-security-fundamentals/topic/blefund-lesson-5-exercise-1/">https://academy.nordicsemi.com/courses/bluetooth-low-energy-fundamentals/lessons/lesson-5-bluetooth-le-security-fundamentals/topic/blefund-lesson-5-exercise-1/</a>.&nbsp;</p> <p>Regards,<br />Amanda H.</p><div style="clear:both;"></div>