Abstract: A communication system including: a P2MP root device, configured to communicate with multiple P2MP user-end devices over a shared network accessible to each of the P2MP user-end devices; and multiple adaptors, each being connected between a first pan and a second part of a respective Pt2Pt communication line, and also connected to the P2MP root communication device by a respective P2MP communication line. Each of the adaptors is configured to: transfer Pt2Pt electric signals of Pt2Pt communication between the first and the second parts of the respective Pt2Pt communication line; transfer P2MP electric signals of P2MP communication between the second part of the respective Pt2Pt communication line and the respective P2MP communication line; and passively convert between the P2MP electric signals which are transferred over the respective P2MP communication line and the P2MP electric signals of the P2MP communication transferred over the second part of the respective Pt2Pt communication line.