Question about Devolo Magic 2 LAN Starter Kit 1-1-2

Yes, because Powerline/dLan uses the phase and the neutral conductor for data transmission, there is actually no transmission if different phases want to be used. However, a (probably rather poor) connection can occur if somewhere (e.g. in the electrical distributor/fuse box) the three phases run directly parallel to each other over a short distance, so that the signal can crosstalk from one phase to the other.
There are phase couplers to enable or improve connections via different phases. However, they must be installed by specialists.
https://www.allnet.de/at...

Basically, the same applies to Powerline/dLan as to Wlan. It may work, but it doesn't have to.