Wifi routers almost never have a grounded plug, unfortunately.
For cost, certification and safety reasons, we cannot modify the power supply by default. Our addition to the router is in the operating system. If we would modify the hardware, we would also lose our warranty claim against Asus.
Grounding the router could only be a problem if you connect ungrounded computer equipment to one of the router ports via a LAN cable.
If you really wanted to electrically ground the eco-wifi router you would need to use something like this from Biologa, a usb-to-ground adapter, and plug it into the router’s usb port.