Nope, that's what we call Power line communication (also known as 'Homeplug'), internet through your home electricity powerlines. Wireless is what is says: no wires, not even electricity wires.

I'm incliden to say that the powerline adapters can equally be the cause. Just make sure you can eliminate the powerline internet from being the cause of the problems. Powerline
can work great but does not always deliver good quality (interference, different groups).
- connect the powerline directly into the wall socket (no extention cable);
- when you have multiple wall sockets (usually two next to eachother), do not use the other connection
To eliminate the powerline adapters:
1. plug the receiving powerline adapter in a very nearby wall socket, preferably one that is connect in the same socket 'grouping' (phase). If the signal is OK (no on/off), the electricty powerline is the cause (redesigning your home electricty plan is the only soltion/ bridging differtent groups (can be dangerous))
2. The powerline adapters can be configured (fixed IP, use DHCP). Try different settings.