They basically turn all the electrical wires in your house into a giant antenna and radiate broadband noise.
And they do it very poorly, I've never been able to get powerline networking to work well. I had trouble reaching the Wifi node in my office from the bedroom on the far side of the house, I thought powerline networking was the answer, but the link was not that fast (around 10mbit), with very variable latency, anywhere from 5msec to 100msec, and around 2% packet drops. Both outlets were on the same leg of my home power panel, I verified it at the breaker box.
I finally ended up putting up a couple Unifi Nanostation M2's (the bigger ones with the 10dBi antennas) aimed at each other through the walls to act as a point to point network, and it was faster and more reliable. Still not super fast, I get like 30mbit, but latency is a nice constant 7msec, with little packet loss.
But in a previous house, the walls were real plaster with metal lath behind acting as a faraday cage, and I had no choice but to use powerline networking (it was a rental house, so I couldn't easily run ethernet)
And they do it very poorly, I've never been able to get powerline networking to work well. I had trouble reaching the Wifi node in my office from the bedroom on the far side of the house, I thought powerline networking was the answer, but the link was not that fast (around 10mbit), with very variable latency, anywhere from 5msec to 100msec, and around 2% packet drops. Both outlets were on the same leg of my home power panel, I verified it at the breaker box.
I finally ended up putting up a couple Unifi Nanostation M2's (the bigger ones with the 10dBi antennas) aimed at each other through the walls to act as a point to point network, and it was faster and more reliable. Still not super fast, I get like 30mbit, but latency is a nice constant 7msec, with little packet loss.
But in a previous house, the walls were real plaster with metal lath behind acting as a faraday cage, and I had no choice but to use powerline networking (it was a rental house, so I couldn't easily run ethernet)