Now that I'm experimenting with remote control software on the HTC Desire HD, it turns out I need to setup port forwarding on the Netgear router.
Port forward configuration
On most routers I've seen port forwarding is a straightforward process. There's a page in the web-based configuration specifically for setting this up. Not so on the NetGear DG834Gv5.
|Netgear DG834Gv5 Services|
|Add the firewall rule, apply, and you're done|
It's as simple as that once you know how to do it. Information on how to setup port forwarding came from PortForward.com. It's a great resource for port forward setup of a lot of routers.