Powerline Connectivity

There seems to be a lot of confusion in these posts about the concept of a "circuit".
Most houses in the USA are wired with 240 volt service, created from two separate 120 volt "phases". The common connection between the phases will be back at a common transformer somewhere in the power utility system. Devices that rely on information transmission over power lines usually will not connect across the two phases. Each 120 volt household wiring branch, controlled by a circuit breaker, is connected to one of the two phases, therefore two household "circuits" in the context of the forum posts.
I can't see any reason why a circuit breaker should inhibit transmission. Nor, in fact, should a breaker panel, if they are wired from the same power entry. Limitations of distance and interference due to noise will still be a limiting factor. Power usage by other devices should not be a limitation since the household wiring is designed to accommodate that. However, high power usage equipment frequently contains motors that create a fair amount of interference. Devices that operate by RF energy, such as microwave ovens, are an obvious source of interference
Other manufacturers of devices using power lines for signal or data transfer provide means of bridging the phases, either by wireless devices that communicate between connection on each phase, or bridge devices installed in the breaker panel (hopefully by a licensed electrician). Netgear doesn't seem to offer such capability. The suggestion to assure that connections are on the same "circuit", in reality the same phase, seem disingenuous, in that the intent of the system is to connect to equipment in separated locations and placing the connection point in another room is not a great solution.