I bought ami2pc linkup from epic about 1999ish. I had problems with it too, basically is {bleep}.
First I thought they had sent me a bad cable so I sent it back and got a replacement, still didn't work. In the end I found after some fiddling and only if I booted from the floppy diskette it would work.
Amigastuff are epic marketing, as far as I know its theit 3rd name change since they were epic, they were awfull ripoff merchants, supplying commercial games on cd-r etc.
In the ned I sacked off ami2pc and just bought a cheep ethernet card that gave me full network and internet access.