Search the OpenWrt forum for "MR3420 v5" padavan or "MR3420 v5 OpenWrt" . Russian and Polish communities have produced stable builds using the firmware (a fork of Asuswrt for MediaTek).
The v5 firmware provides a comprehensive suite of management tools: Connectivity Management tplink mr3420 v5 firmware
. While it supports standard WAN connections, its primary feature is a USB 2.0 port for 3G/4G modems, allowing it to serve as a failover or primary internet source www.tp-link.com Official Firmware Features Search the OpenWrt forum for "MR3420 v5" padavan
There are two primary ways to update your TL-MR3420 V5: manually through the web interface or via the TP-Link Tether app. Download for TL-MR3420 V5 - TP-Link tplink mr3420 v5 firmware