The router has it's own power (12v).
I leave the GoFree in what's called "infrastructure mode". Can't recall if that's the same terminology that the Zeus uses.
So the zeus has Internet access and can access predictwind and download updates. And any device that connects to the GoFree has Internet access. Laptops, tablets, phones etc..
And my navionics boating app just sees the zeus and can do the updates, get nav data, share wpts and other apps can get nmea data from the zeus.
Yes I have a 4G subscription for the router.