Indeed it all began with networking CP/M computers.
Around 1981 Novell
came to the market with their first networking ??>product,
called S-net.
Back in 1984 we used a star network device to network some DEC Rainbows
and PC's (both running MS-DOS). I don't remember who made it, but I
really don't think it was Novell. It was a specialized box though. The
wires that connected to the Rainbows and PC's connected with little
slip-on clips that came off quite easily.