Im more inclined to say you have a transmission problem than a version
one.
Smaller transmission windows in v2 may be hiding a performance issue in
your
LAN/WAN that v3 has a problem with.
I concur. This is the most likely explanation. Tune your block size for NFSv3 down to 16K or 8K and see how you do.
End resuly may be going to TCP to introduce more reliable error
correction.
I'd stick with UDP and a smaller block size.
Bruce