NFS v2 support from Linux is Okay... Has a set of issues...

NFS v3 support from Linux is Okay... Has a different set of issues...

What do the Exports look like in /etc/exports

Are you running lockd on the Linux box?

And are the "Secure or Insecure" mount requests? If they are secure, Someone has to login that has rights to the export from the machine doing the request... or you have to tell it (the exporter) to allow anyway...