I know this topic appears from time to time in the list archive.
But have you ever seen this much?

Below is the dmesg of NFS client (macppc/1.6.1_RC2). The server is an i386.
I mounted "pkgsrc" and compiled shells/zsh. I tried some combinations
of "-2" and "-T", but the results were the same.

What is worse, when I tried "-r" and "-w" in order to lower the size,
random errors occured, e.g. patch didn't work.

Any suggestions except for replacing the NIC?
(This machine is mainly for MacOS.)

Mar  2 17:43:27 starmax /netbsd: rtk0: transmit underrun; new threshold: 320 bytes
Mar  2 17:45:43 starmax /netbsd: rtk0: transmit underrun; new threshold: 384 bytes
Mar  2 17:45:54 starmax /netbsd: rtk0: transmit underrun; new threshold: 448 bytes
Mar  2 17:46:05 starmax /netbsd: rtk0: transmit underrun; new threshold: 512 bytes
Mar  2 17:46:10 starmax /netbsd: rtk0: transmit underrun; new threshold: 576 bytes
Mar  2 17:46:25 starmax /netbsd: rtk0: transmit underrun; new threshold: 640 bytes
Mar  2 17:46:27 starmax /netbsd: rtk0: transmit underrun; new threshold: 704 bytes
Mar  2 17:49:27 starmax /netbsd: rtk0: transmit underrun; new threshold: 768 bytes
Mar  2 18:11:04 starmax /netbsd: rtk0: transmit underrun; new threshold: 832 bytes