I remember it working with 3.1 even, although it wasn't built in (needed something called Trumpet Winsock). '98se had connection sharing (I thought I remembered that '95 did too, but Wikipedia says no... maybe it's that it came with something to install on '95 machines that would let them be clients? I know for a while we had an XP machine with the modem, and a '95 machine that could see the internet through it.), which did for your dial-up much the same thing that your home router does now for your cable/dsl.