Mounting modern NFS shares on old Solaris versions like 2.6 might be troublesome. NFSv4 is not supported, and UDP protocol is disabled on modern NFS implementations like TrueNAS SCALE.

But with the line below in /etc/vfstab, it's fairly simple:

<nfs_server_fqdn>:<remote_path> - <local_path> nfs - yes vers=3,proto=tcp,rw,bg,hard,intr,rsize=32768,wsize=32768