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If you happen to brick your router, do not fear. You can use TFTP file transfer to flash the router with a new firmware.

You need:

• A TFTP client for your computer. There are both command-line tools and GUI versions available.
• Your computer must have an IP address from the 192.168.1.x network, as the router failsafe mode defaults to 192.168.1.1.
• A new firmware to flash in. Either an original Netgear firmware or an Openwrt «factory.img» firmware. «Sysupgrade» version will not work.
• Access to router’s reset button

1. Configure your ethernet connection (on the client machine you’re using to configure the WNDR3800) using a static IP as 192.168.1.2, netmask 255.255.255.0. (The WNDR3800 in factory reset mode is going to come up as 192.168.1.1.)
2. Connect your computer to one of the LAN (not WAN) ports on the router.
3. Start a continuous ping from your client computer to 192.168.1.1 (Linux and Mac OS ping will continue until stopped by default; Windows ping by default sends 4 pings and then stops, so use «ping -t» under Windows); probably nothing will answer these pings yet, but you can use the output to tell you when the router is ready in the next couple steps.
4. Power the router off.
5. Hold down the factory reset button on the bottom of the case. Now turn the router back on while continuing to hold the factory reset button…
6. Wait until the router is listening on 192.168.1.1 (this takes 45-60 seconds; to confirm, you can ping 192.168.1.1, and see if it responds; it’s best to start a sequence of ping requests above, before your hands get busy with the factory reset button).
7. Release the factory reset button. (If you happen to have a serial cable connected, you’ll see that the system is in firmware recovery mode and that it will be waiting for you to upload firmware. But you don’t need the serial cable at all.)
8. Run a tftp CLIENT on your computer (enter no hostname on the command line), set trasfer mode to binary and retransmit timeout to one second (optional), next put firmware image to router.

For the linux tftp client enter the following (note «rexmt 1»! Some people do not see «1» and enter «binary» as the value for rexmt, thus they do not switch to the binary mode, and upload doesn’t start):

If successful, you will see upload progress info for a couple of seconds, then the router will flash itself and reboot automatically. This may take several minutes. Be patient, don’t reset or switch off a router!