Are you looking to or install a custom ROM like OpenWrt ? What operating system is your computer running?
Device Page: tl-mr3420_v5 Forum search: TL-MR3420 v5 Git search: TL-MR3420 v5 OEM Device Homepage URL: https://www.tp-link.com/en/ Download for TL-MR3420 V5 - TP-Link tplink mr3420 v5 firmware
Under the "Local Upgrade" section, click the or Choose File button. Select the extracted .bin firmware file from your computer. Click the Upgrade button. Are you looking to or install a custom ROM like OpenWrt
Before building from source, check if a pre-built "Factory" image exists on the OpenWrt Table of Hardware for MR3420 v5. If it does, download it and flash it to test hardware functionality first. If it works, you can then compile your own image using the exact same profile settings. tplink mr3420 v5 firmware