https://devzone.nordicsemi.com/f/nordic-q-a/22055/can-not-connect-to-devices-with-sdk-13-from-android-4-4-4Hi, I use the NRF-toolbox app&#39;s UART feature for connecting to nordic devices. Android version is 4.4.4 and the device used is a Samsung device. Everything was working fine when nordic device was using SDK 11, Softdevice S132 v3. But after migrationen-USTelligent Community 13Thu, 18 May 2017 05:23:09 GMThttps://devzone.nordicsemi.com/thread/86571?ContentTypeID=1Thu, 18 May 2017 05:23:09 GMT137ad170-7792-4731-bb38-c0d22fbe4515:637527ab-bc83-4f20-b4d6-3d0d026eb370Sourabh Barve<p>Thanks Kristin. It worked. If only nrf_ble_gatt_init() is commented instead of entire gatt_init(), it also works on devices supporting BLE4.2.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/86570?ContentTypeID=1Tue, 16 May 2017 13:04:08 GMT137ad170-7792-4731-bb38-c0d22fbe4515:fb072c64-6452-4f21-a3a4-05f51ca9aee4FormerMember<p>In SDK 13, a &quot;GATT module&quot; was introduced and is enabled by default. This module enables MTU request and Data Packet Length extension (DLE). For all phones supporting BLE 4.2 and above, the examples in the SDK will work out of the box.</p> <p>For phones that support BLE 4.0 and/or BLE 4.1 only, MTU request and DLE will not work. In that case, you will have to disable it in the SDK example: all you need to do is to comment out <code>gatt_init()</code>.</p><div style="clear:both;"></div>