https://openwrt.org/toh/tp-link/tl-mr3420
The Install Image Link for the V2.3 leads to a 404:
http://downloads.openwrt.org/releases/17.01.6/targets/ar71xx/generic/openwrt-17.01.6-ar71xx-generic-tl-mr3420-v2-squashfs-factory.bin
Browsing the Server there is a different image:
http://downloads.openwrt.org/releases/17.01.6/targets/ar71xx/generic/**lede-**17.01.6-ar71xx-generic-tl-mr3420-v2-squashfs-factory.bin
So difference is /openwrt to /lede, is it actually the same ?