Also known as "R4A Gigabit". On the back it just says "R4A" but plugging into ethernet can verify that it's the gigabit edition.
Click through initial setup wizard in chinese accepting defaults. When asked for a wifi password know that this will also be the admin password. If connected through wifi you will be disconnected at the end of the wizard since the wifi now has a password. Reconnect and go to the web admin again. Type in the wifi pass in the text box and once you're logged in the stok will be in the address bar.
The latest OpenWRTInvasion repo has both stock firmware and working openwrt images. The stock firmware version from the repo miwifi_r4a_firmware_72d65_2.28.62.bin works fine.
Don't use the latest version of OpenWRTInvasion. It does not seem to work. Instead use the v0.0.1 version.
Use python3 -m http.server to serve up a sysupgrade firmware (probably the one from OpenWRTInvasion repo as others have been said to brick the router).