Most people who have an Internet box can hook up a power-line adapter.
It's okay as long as the line is steady, which isn't often. The signal can be weakened by "problems" like multiple outlets or having to pass through the meter. It can disrupt certain radio frequencies (input grid...). Not appropriate in a three phase environment
It's not the best solution for data confidentiality either. There is also the problem of a power outage but in that case, most devices stop working anyway...
The most reliable method is still direct connection via cable or Wifi network.
All the best for 2016