try this.

echo flush >'#a/arp/data' on v2 cpu/terminal

arp flush (i think) on a v2 file server console

and things might spring to life.

by changing the card you changed the MAC address
and thus the IP to MAC translation
but v2 systems will still retain the original translation until
you tell it otherwise.  they will be sending to the card
that's now truly on the ether (out in the air).