I don't have Dish and I don't work for Dish, so I can't be authoritative
about what Dish is doing. But ...
They could be using udp/2049 for any protocol. If you can sniff the
connection with something like wireshark, do the dissectors say it's
valid nfs?
I'll try using tcpdump. I don't have wireshar.
You'll have be to pretty verbose with tcpdump, -vv at least, and capture
the whole packet with -s 0. Even so, see if you can try out Wireshark
(previously known as Ethereal). It's pretty handy for digging around
inside captured packets.