On the switch the light is green either for IIcx or 6100.
Seems to me that the Card itself is correctly installed. Switching the Apple-Talk from "printer" to "Ethernet Slot3" does not work on System7.
I think my switch is up to Gigabit, but I also use 10Mbit card on another PC and it's working fine, so I don't suggest the switch being the problem.