Many devices by default use DHCP to obtain their IP address on your home network. What this means is that the device tells your router, "I want to connect to the network" and the router replies back with "Okay. Here is your address so that you can be found on the network." After a certain period of time, that address will expire and the device will again ask the router to connect to the network. Sometimes the router will assign that device the same address, but often times it will assign it a different one instead.
Normally this is a quick and simple process that is transparent to the end-user. However, problems can arise when other applications or devices expect to find that device at a certain address but it is suddenly not available. When this happens in a DirecTV Remote app, the result is that the app can no longer control (communicate with) the receiver.
There are two solutions to prevent this from ever happening again:
1) If your router supports it, set up DHCP Reservation for each of your receivers. This forces the router to always assign the same IP address to the device in question (in this case, your DirecTV receiver). This is usually relatively easy to set up, but not all routers have this feature. Please consult the documentation included with your router to find out how you can do this.
2) An alternative to #1 is to use static IP addresses in your DirecTV receivers. This is similar to DHCP reservation, but is done the other way around. Instead of making a change in your router's settings, you make a change in the DirecTV receiver's settings. All routers allow this, but before you do this though, you should try to consult your router's documentation to first determine which IP addresses are allocated to its DHCP pool. The reason being, you do not want to assign a static IP address to a device that the router thinks it should be able to hand out freely. Theoretically, it should not re-assign an IP address that is already in use, but it is good practice to avoid using DHCP addresses as a static address.
Valid addresses are typically 192.168.1.2 - 192.168.1.254 (note that the first three sets of numbers, 192.168.1, may vary depending on the router). Most home routers do not use DHCP in the higher address range, so unless another device is using the same IP address you choose, you could probably get away with using an address over 200 as a 'quick and dirty' attempt. What this means is that you might try 192.168.1.201 for your first receiver and 192.168.1.202 for your second receiver, and so on. Just remember that when setting up a static IP address in your receiver, you should ONLY change the last portion of the IP address (192.168.1.xxx). Many home routers use 192.168.1.xxx but not all do, so you do not want to change those first three sets of numbers. PortForward.com has excellent information on many makes and models of routers and would be an excellent place to start whether you are thinking about trying option #1 or option #2. Should you decide to go with a static IP address on your receiver, here's how to do it:
Go to MENU > PARENTAL, FAV'S & SETUP > SYSTEM SETUP > NETWORK SETUP then choose ADVANCED SETUP. Here, you can adjust the IP address by changing the numbers in the last box (i.e. 192.168.1.xxx). Choose numbers outside of your router's DHCP range and ones that are not already assigned to another device. When finished, click on CONNECT NOW. If all goes well, it will report back that everything is working correctly. If for some reason you seem to have problems with your new static IP address, you can choose RESTORE DEFAULTS which will allow the receiver to obtain its own address using DHCP.
NOTE: It has been reported by a Linksys WRT600N router owner that assigning a static IP address outside of the DHCP range did not allow the app to communicate with the receiver. After changing the static IP address to a number within the DHCP range, it did communicate. So if you are trying to use a static IP address in your receiver without any luck then you might want to try using an address within the DHCP range. Even if it is not a Linksys brand router it is worth a try. Just be sure that nothing else is assigned to the address you choose. Many router configuration pages have a section that shows a list of devices that are currently connected using DHCP.