Brand : RP-LINK
Model : RP-W402
CPU : MediaTek MT7620N 580MHz
ROM : 8M SPI Flash
RAM : 64MB DDR2
2.4G WiFi : 2*2（Support IEEE 802.11N，300Mbps）
2.4GHz Channel： 1,2,3,4,5,6,7,8,9,10,11,12,13
5G WiFi : NO
4 10/100M LAN
1 10/100M WAN
1 USB2.0 input
1 RESET button
1 charge input（9V 500mA）
This device is not yet supported by OpenWrt.
Please come back once there are significant efforts visible to get this device supported.
I should say that actually it is supported by OpenWrt . I flashed my device with an openwrt image for another device that is familiar with mine, it worked but not stable.
Actually openwrt supports my device and it should be modified to support perfect.