Ugh.  I've had a lot of issues with ethernet cards and the SE/30.  Even when I had the actual software disk, I couldn't get them to work by just installing the card and drivers.  The only way I could get them to work is to do a clean install of System 7 with ALL the network options selected.

After that, I didn't even need the driver disk that came with the card.  It would work with the Apple software.  Then I'd install MacTCP and it'd work fine.