Thank you for the link. I did read that first before posting, hoping for some enlightenment. The problem is that Asante wrote the documentation when only OS 7 was avaialable (AFAICT) and there are no notes about compatibility with later software.
Hmmm. So 8.6 on an 8100 is somewhat different territory. Will 68K Macs run 8.6? I can't remember what the machine-OS limit is any more. It's possible that they never tested out 8.6 or 9.1 because only the PPC NuBus machines could go that high.
At any rate, I used the built-in ethernet, and it worked flawlessly to transfer the files. It was probably a little slower than the 10/100 would have been, but I could have spent hours fiddling to get the 10/100 to work, so just going ahead with the built-in was probably faster.
Tyler, if you ever find you can't live without a 10/100 NuBus card let me know. I'll sell you one for $25 plus shipping. I have a few refurbished (from Asante) units in the box which have not been used.