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How to flash RT-N66U with Shibby's TomatoUSB firmware


Download Asus RT-N66U Flash utility

Download Shibby RT-N66U firmware

K26RT-N is appropriate for the RT-N66U. Go ahead and pick the latest release by date. Inside that directory you want the to pick the Asus RT-N66u 64k. The 64k in the name means that 64k of flash memory will be used as NVRAM. Inside that directory the .trx file with AIO in the name has all possible features compiled in and enabled. If this is your first time installing, AIO is a good jumping off point.

Preparing for firmware restoration to TomatoUSB (Shibby)

The steps are simple, you will need to:

  1. Connect the ASUS RT-N66U to your network
  2. Start the firmware restoration process (using firmware restoration utility in the ASUS Utility package) so that it is searching for router
  3. Put the ASUS RT-N66U into firmware restoration mode and start the firmware restoration process

Before you proceed, pull out the power cable to your RT-N66U and have a pen ready to press the reset button (between the USB ports and WAN port)

Flash the TomatoUSB firmware onto the RT-N66U.

  1. Launch the firmware restoration utility (this is one of the tools in the Utility you installed earlier)
  2. In the firmware restoration utility, browse for the TomatoUSB firmware you have downloaded earlier
  3. Start the firmware flashing and a prompt should appear stating that it is an incompatible firmware. Proceed to the next step.

Putting the RT-N66U into emergency firmware restore mode

  1. Press and hold on to the reset button
  2. While holding down the reset button, plug in the power cable so that the RT-N66U turns on. Note: Keep holding the reset button until the power led starts to flash (on and off). When power led starts flashing, release the reset button and proceed.
  3. On the firmware restoration utility, agree to the prompt saying that it is a incompatible firmware. The utility should be scanning for device. Proceed to the next step
  4. Wait until the flashing is complete
  5. The router will automatically power cycle when it is complete

Finally, clearing the NVRAM before you use TomatoUSB

It is always a good practice to clear out the previous settings (in NVRAM) whenever you flash to different firmwares. This is true for PC BIOSs as well. In this case, it is required to flush out the NVRAM from values that may have been previously stored by the stock firmware that are no longer valid for TomatoUSB.

You can either flush the NVRAM either through key presses or through web admin.

Clearing NVRAM via key presses

  1. Power off the RT-N66U
  2. Press and hold down the WPS button
  3. While holding the WPS button, plug in the power cable to turn RT-N66U on
  4. Keep holding the WPS button for 30 seconds before releasing The router should reboot
  5. Congratulations. The NVRAM has been cleared.

Clearing NVRAM via web admin

The TomatoUSB administration web should be at If it is not, do a “ipconfig” or “ifconfig” and navigate to the gateway address with your web browser. If you are not able to get an IP address from DHCP, you might want to set your computer’s IP address to

When prompted for a login, the default is:

  • User: root
  • Pass: admin

Once you are in, follow the next step to clear out the previous settings

  1. Navigate to Administration -> Configuration
  2. Under Restore Default Configuration, select “Erase all data in NVRAM memory (thorough)
  3. Click “OK”
  4. Wait for the router to be ready
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I was having real trouble getting larger images to flash at all, either through the recovery app, the web UI, or TFTP. I ended up searching for the smallest image I could find, and used tomato-K26-1.28.RT-N5x-MIPSR2-120-MiniVPN.trx. From there, I could flash a recent all-in-one image.

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Process that worked for me on a Mac:

  • Install the asus device discovery and firmware flash utils from app store
  • Reset NVRAM (not sure if necessary, but why not) using steps above
  • Put it into emergency firmware restore mode (otherwise the upload craps out at about 25%) using steps above
  • Upload a small tomato firmware, I just used because @deviantintegral recommended it. This is because the finicky part of this process seems to be going from Asus -> tomato.
  • Reset it manually (toggle switch on and off)
  • Wait for a new DHCP address (about 30 seconds)
  • Installed a fully featured, recent all-in-one image, checking the "clear NVRAM on reboot" setting so that it automatically clears the NVRAM again. This takes a few minutes to upload and reboot, and will reboot a couple of times, but the Web UI is very informative on the progress.
  • Confirm the new firmware version
  • Enjoy my new, recent, tomato firmware.

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Double check the version of your router. I've spent some time following the instruction here without success. Finally I've double checked and it seems ASUS released a "B1" hardware version of RT-AC66U, which is not compatible with all previous generation firmwares for RT-AC66U (A1).

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@tomaszkoperski: Do you know if there's a tomato-shibby (or AdvancedTomato) version that is compatible with the RT-AC66U_B1 hardware revision?

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Is there any newer Tomato than from 2015? The file I am looking at doesn't have the same naming schematic as the one to poster says...

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Trefilov22 commented Apr 21, 2017

And why couldn't you use the firmware update option from inside the Router? I only ask this because my laptop doesn't have an ethernet port to connect directly to the router, I pretty much have to do everything thru WiFi...

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kikiSK commented May 14, 2017

I ask for help.
How to connect Asus VDSL AC68U / main router / and Asus RT N66U Tomato 1.28 shibby I think Lan to WAN port

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I have the RT-66R router, will this firmware work on this one too?

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quangv commented Oct 26, 2017

anybody have a mirror of this? is down for me

edit: yeup, it's back

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stullekovski commented Oct 29, 2017

Looking for the same as @quangv. is still down.
Especially for versions before 138 MultiWAN for my RT-N66U. Thanks a lot!

Edit: it's back online.

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Thanks @docbill @AaronCompNetSys, excellent instructions. Anyone else who arrives here: take what people are saying about loooooong reboot time seriously. For me it was like 20 minutes after seeing "Failed to connect to the wireless router. Check if the router's power LED is blinking, which denotes rescue mode".

Finding the smallest possible Tomato firmware to initially install, and then installing your desired one from there, sounds like the way to go; that's what I would try if I (shudder) had to do this again.

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saulp commented Mar 30, 2019


Skip the instructions in the original post. Read docbill's and AaronCompNetSys' instructions first.

Especially the second link, with the process to simply skip the unnecessary and frankly crappy Asus software:

1. docbill

2. AaronCompNetSys

(thank you both!)

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What worked for me was to flash the DD-WRT firmware from the console administration web console, then flash the shibby firmware from the DD-WRT admin web console.

This is so much easier lol. Idk why anyone is doing it any other way. Fk that.

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