I am using the Yinuo-link router YN-Q418( (price 350 CNY).
It is a IPQ4019 device with 256MB or RAM, 2M FLASH + 128MB of NAND flash and 1 GigE ports ,2.4G & 5G WIFI,USB3.0,USB2.0,two miniPCIE.
I have change rt-ac58u dts to support this device.
maybe I should share the patch to support this device.