Unintentional vs. Intentional Radiators
Here in the U.S. the Part 15 mentions unintentional and intentional radiators. Well, if you have a motor, printer or other similar device radiates interference, it was not meant to do so and the interference is unintentional. It can also be mitigated by filtering with EMI suppressor sleeves on the cables, for example. These are the black bulges on the ends of the cable.
But now you have this power line ethernet device where the whole design is centered around the transmission (and incidental radiation) of high frequency energy over bare wires. If that isn't intentional, I don't know what is. If you try to get rid of it by filtering it out., the whole system stops working. In other words, the system is built in such as way as to purposely interfere with other nearby equipment.
I saw these were now available at the Microcenter store in their ads last week. FIrst off, I would never put one in service on my premises, because of the interference. Second, has anyone looked into the security of these signals? Can just anyone decode the radiated signals and find your private information? I would never trust them because of this risk.
Another problem that can happen with commercial installations where three phase power is used is that the sending equipment is on one phase, and the receiving equipment on another phase. So you end up with spotty or no communication.
Just use WiFi, or regular cat5 wiring. Just say NO to this junk.