I'm no expert, but my gut and my troubleshooting rules ask: what IS different?
-CAT cables all good?
-addreses/IP table(s)
-controller model?
-controller FW?
-is it a managed switch?
SOMETHING must be different, although I've seen some weird things.
One time I had to deal with a Serial cable that pinned out fine (through the connectors as well) but the item wouldn't respond.
After making another one, it worked fine. Put the old one back and it would not.
Go figure. We never did find out why.
Good luck, and let us know what happens!
