How do I find out what the Link Quality of my HomePlug device is?

Run the HomePlug Configuration Utility for each corresponding model, and select the Device tab from the Powerline menu.

The Link Quality is shown here.

Alternatively check the colour of the Powerline LED on each unit:

Powerline LEDConnection Rate
NoneNo activity
Red (good)Less than 30 Mbps
Amber (better)Between 30 - 80 Mbps
Green (best)More than 80 Mbps