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Oh, That Explains It
I just decided to look up the word "teredo" on line. Its exact meaning had escaped me, and I needed more. And this is what Wikipedia offered me:
"Teredo is a tunneling protocol designed to grant IPv6 connectivity to nodes that are located behind IPv6-unaware NAT devices. It defines a way of encapsulating IPv6 packets within IPv4 UDP datagrams that can be routed through NAT devices and on the IPv4 internet."
That cleared things up.