Greetings,
I'm using the IDE64 along with the ETH64 card, my IDE64 is an older version (long one, no cf), and with the help of Soci the firmware was patched so that it would work.
Have you verified that eth1 is NIC that is connected to the same switch as the C64 ?
Have you verified that 00 ($C64:NET) is indeed the lsat byte of the MAC address and that the other numbers also match?
If these are correct, try and use a direct-connection as your switch MAY (for reasons I couldn't explain) not be directing the packet to your C64 ethernet port.