You join all six adapters into the same powerline network. Start with a paired kit, and then add the others one by one as described in the manual. Do not attempt to run three separate powerline...

Whichever - for a factory reset, just hold the button pressed for a long time until something happens on the LEDs, then let go of it, and wait until the LEDs come back to normal.

Here's what I do to deploy a new pair of PLCs. Grab a powerstrip. Plug each one PLC in, wait until it is ready, then hold the button pressed until the status LED turns back off.Wait until the LEDs...

Did you have them in close proximity while pairing?

So you need to pair the two adapters using whichever method you choose - utility program or pushbutton on the device.

Guys, please remember that PLC firmware is country specific for regulatory reasons. If you're running another country's firmware, you have a certain chance of your device emissions disturbing...