A friend of mine uses an adapter like this to have ethernet available all over his house. He uses a different model, but the idea is the same. Robert Heron recommended this model so for $34 it seemed like a steal.
The idea is to attach one to your router and plug it into an electrical outlet. Don’t use a power strip adapter. You plug the other one into the outlet where you want the new ethernet. You press a button on one adapter and then go down to the second adapter and press the button on it. It then connects and you are on the internet.
I’m not sure what the small CD is for.I did not need it.
Zyxel also has a four port model for $80.00
Here are some Speedof.me test results – download/upload speeds.
Upstairs direct connection to router – 17.5/3.5
Laptop on wireless – 15.2/3.5
Laptop on adapter – 17.3/3.5