Sorry to take so long to respond... unfortunately I think the device I was remembering was the HDMI over 2-conductor that was linked and not Ethernet over 2-conductor.

I'd already found the other devices linked.  Application would be for running Ethernet over non-category wire (not necessary extending it), but looks like the NVT device can do up to 750ft over 18/2 or 500ft over shielded twisted pair which would work.

Thinking ahead for HomeWorks upgrade projects where there is QS link wire which is usually a pair of unshielded 18 AWG plus a pair of shielded 22 AWG wires between processors.  The new processors require Ethernet between them and it's not always possible to pull a CAT5/6, but the NVT device should work well on the QS Link wire that's already in place between processors.