The stock firmware on the ASUS RT-N66U might not be too bad, but why settle for it when you can use Tomato instead? Follow these easy steps to install Tomato.

Ever since I started to host this site on VBOX, I’ve gone to ridiculous lengths to make sure the server is up and online as much as possible: The server, the internet modem and a router is connected to an APC UPS and I’ve registered the server as a Ripe Atlas node to measure uptime. This weekend I also got a spare router, just in case the one I’m currently using goes tits-up. If it does, it’s not the availability of VBOX that concerns me, though: I wouldn’t have wireless internet in the apartment. What would happen then, maybe I would have to read a printed newspaper, like a caveman?

So I bought another ASUS RT-N66U router, just to be on the safe side. It’s a proper workhorse and a great piece of hardware, but it has a bit to be desired on the firmware front. Thankfully, there are some very clever people out there. People so clever, they’re making custom firmware for routers. One of these custom firmwares is Tomato (Wikipedia). The base build hasn’t been updated in the last couple of years, but some of the Tomato modifications are very active. One of these modifications is Shibby’s, and that’s the version we’ll be flashing.

Warning: Flashing third party firmware will void your warranty. I will not be held responsible if anything goes wrong. Flashing a device’s firmware is always a risky operation, especially when you’re dealing with custom, unofficial firmware. By following this amateurish guide you understand that you might end up with a brick - a useless piece of hardware.

Another warning: Flashing a router with third party firmware isn’t a trivial thing to do, even with the help of this step-by-step guide. Make sure you read through the entire guide at least once before you start so you get an overview of the steps.

With that out of the way, let’s get started (if you are running into any problems along the way, I strongly recommend that you read the comments to this post, as other people might have had the same problem and found a solution).

1. Download and install the ASUS RT-N66U Firmware Restoration utility from ASUS’ support site. Just enter RT-N66U in the search box and you should be able to find it.
2. Download the latest version of Shibby’s RT-N66U firmware. Go for one of the ASUS RT-N66u 64K versions. Any of them will work great, take the one with features that best suit your needs. If you’re not sure what your needs are, download the AIO version. There are two language versions on Shibby’s site, one Polish and one English; The Polish version is in the directory ending with -PL, the English version in the directory ending with -EN. So make sure you’re downloading the correct one.
3. Connect the RT-N66U to your network with a network cable, but don’t turn it on yet. If you have more ASUS routers connected to your network, make sure you isolate the one you will be flashing, or you run the risk of flashing the wrong router (or at least that’s my theory). Isolating the router can be easily achieved by connecting it directly to your computer with a network cable (make sure you connect the network cable to one of the LAN ports on the router, and not the WAN port) and disconnecting your computer from any wireless network you might be connected to.  At this point you don’t need an internet connection (since you have all the files you need now and you see this guide).
4. Open the ASUS Firmware Restoration utility and load Shibby’s RT-N66U firmare, but don’t start the restoration process just yet.
5. If the RT-N66U is on, turn it off.
6. While holding the reset button, turn the router on. After a short while, the power LED should start blinking. Release the reset button. The router is now in emergency firmware restore mode, ready to be flashed.
7. Start the restoration process in the ASUS Firmware Restoration utility.
8. The utility should upload the firmware to the router and start the restoration process. If you get any warnings that the firmware is unknown, unofficial or similar warnings, just click OK (or similar) and continue. The flashing process might take several minutes. In my case it took more than 5 minutes. Note: Some users have reported that they get an error message (screenshot) from the firmware restoration utility. It seems like the reason for the error is that the flashing process is so slow the restoration utility gives up. But the flashing process is still running on the router. The solution is to just wait, but it’s not clear how long you have to wait. One user reported about 15 minutes, another about 30 minutes, so your mileage will vary. After a while, the router will restart itself, and when it’s done restarting itself, the Wi-Fi light will be turned on. It’s then time to move to the next step.
9. When the router restarts as described above or the ASUS Firmware Restoration utility reports that everything went OK, you might not yet be able to connect to the router. But there’s no need to panic, you simply have to clear the NVRAM.
   1. Turn off the RT-N66U.
   2. While holding the WPS button, turn the router on.
   3. Keep holding the WPS button for at least 30 seconds and then release it.
   4. The router should now reboot.
   5. After the router has rebooted, open the browser of your choice and go to http://192.168.1.1/. When prompted to log in, the default user name is root and the default password is admin. You should change the default password after logging in the first time.

Congratulations, you now have one of the finest custom router firmwares available installed on your ASUS RT-N66U.

This guide is based on How to flash RT-N66U with Shibby’s TomatoUSB firmware and ASUS RT-N66U – TomatoUSB firmware Flashing Guide