https://devzone.nordicsemi.com/f/nordic-q-a/83035/download-client-library-not-connecting-again-after-few-attempt-sHi, I am using the download client library (MFW 1.1.4 due to Verizon compatibility) and am noticing that the TLS handshake with my server only succeeds after the first few attempts after a system reboot. I modified the HTTPS Download Client sample byen-USTelligent Community 13Wed, 22 Dec 2021 14:04:58 GMThttps://devzone.nordicsemi.com/thread/344814?ContentTypeID=1Wed, 22 Dec 2021 14:04:58 GMT137ad170-7792-4731-bb38-c0d22fbe4515:076c3ed0-27cd-48b6-9118-48f7563efe4eCharlie<p>Hi Aziz,</p> <p>They are two points you may need to check:</p> <p>1)&nbsp;SSLv3 (aka TLS 1.0) is long deprecated and has some security issues, so you should <a href="https://disablessl3.com/">disable SSLv3 (disablessl3.com)</a>&nbsp;on your server. The version of mbedTLS is&nbsp;2.6.0 according to <a href="https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.8.0/zephyr/releases/release-notes-1.9.html?highlight=mbedtls">Zephyr Kernel 1.9.2 Documentation</a>&nbsp;which is used by NCS1.8.0, so you need to switch to&nbsp;a newer TLS at least 1.2(refer to mbed TLS protocol support table from <a href="https://en.wikipedia.org/wiki/Comparison_of_TLS_implementations">Comparison of TLS implementations</a>).<span></span></p> <p></p> <p>2) Since the latest NCS1.8.0 is not tested with MFW1.1.4 according to <a href="https://infocenter.nordicsemi.com/topic/comp_matrix_nrf9160/COMP/nrf9160/nrf9160_modem_fw.html">Compatibility Matrix</a>, it would be better practice to test with the correct MFW version to avoid struggling with compatibility issues.</p> <p>Best regards,</p> <p>Charlie</p><div style="clear:both;"></div>