One thing Inthought of is the Lumin U1, so I presume the U2!is the same, does not have internal WiFi receivers. You have to hardwire it to you LAN.
The reason, of course, is a wire is (generally) less likely to have issues and, probably more importantly, the receiver:transmission is quite electrically noisy.
you would need a hard wire off your router or some kind of mesh wireless system that will let you run an Ethernet wire to one of the satellites.
several of the others you were looking at were more integrated, for good and bad.