Thanks for the information. My Slingbox defaults to 192.168.0.254, and I know that that's the proper LAN address since I can access the Slingbox locally on the LAN. Since I can't access it from the WAN (i.e., internet) the problem seems to be forwarding the traffic from the public side on port 5001 (or any other port for that matter).
Making the problem even more confusing is that when I use the "My Slingbox Information" link on the support page to see what IP that Sling thinks I'm using, it reports 192.168.0.110. Well, that IP is not in use on my network anywhere. I've returned the PRO-HD to factory setting several times while trying to fix this, and even if I use the 192.168.0.110 address on the Slingbox it doesn't work. Furthermore, the public IP that Sling is reporting is not the address of my router. I'm starting to think that the problem is not local to me, but rather with Sling's data that their server is using to connect.
Does anyone know if there's a way to update the data that my Slingbox is sending to Sling, or if there's a way to determine if the data being sent by my Slingbox to Sling is correct?
I've attached screenshots to illustrate.