If you want to use DirecTV On Demand, but don't want to shell out any more cash for a network adapter to connect to your DirecTV digital video receiver (DVR), and you have a computer with two network adapters, read on.
I recently connected my Apple Mac mini to the digital receiver to take advantage of the DirecTV On Demand service and use the Mac to stream audio from an HP Media Vault. Within a few weeks the Mac went south and I had to come up with a temporary solution to use On Demand. The solution was Windows Internet Connection Sharing on a portable computer.
Your situation may be similar to mine. The DirecTV DVR is nowhere near my wireless router making it unpractical to stretch an Ethernet cable from the router to the receiver. The answer to the problem is to place a computer with a wireless adapter and an Ethernet adapter in close proximity to the receiver, connect the computer to the Internet via the wireless adapter, enable Internet Connection Sharing on the wireless adapter, and connect the HD-DVR to the Ethernet adapter.
Please read this entire post before trying this on your own, and remember - you are attempting this at your own risk. I cannot be held liable for any changes to your equipment that results in any type of loss. If you don't feel comfortable attempting this modification, leave it to an expert to try.
Step 1. Install wired and wireless adapters in your computer, and connect to your home network wirelessly. The assumption here is that you've already done this - maybe you have a laptop computer - and don't want to spend the extra money for the wireless adapter that attaches to the DVR.
Step 2. Enable Internet Connection Sharing on the wireless adapter. Open the properties page for the adapter, click the Advanced tab, and check the box that enables ICS. Key: The process of enabling ICS will configure the Ethernet card with an IP address of 192.168.0.1. Change it to 192.168.2.1 and it will not conflict with any another device on your network.
Step 3. Use a crossover Ethernet cable to connect the computer to the DVR. You can get one from your local electronics store. They come in different lengths, and are inexpensive.
Step 4. Manually configure the DVR network settings. The DirecTV website has concise information on how to do this. Keys: The gateway IP address on the receiver is the IP address of the Ethernet adapter (192.168.2.1). Configure the IP address of the receiver to be 192.168.2.2. The subnet mask is 255.255.255.0. Set the DNS server address to that of your router.
Firewalls
Chances are you won't have to, but you may need to check and adjust your firewall settings. Google "internet connection sharing firewall" for more information.
USB Cable Modem
These instructions might work if a) you have a cable modem, b) your PC is connected to the cable modem via USB, c) your PC has an Ethernet adapter, and d) your DVR is nearby. In this situation enable your USB cable modem connection for ICS and configure as documented above. But you really should get a router or gateway.
Routers act as firewalls and help shield individual computers from being hijacked and turned into zombies. Seriously.