Installing DD-WRT on an ASUS RT-AC66U router

I recently upgraded my EnGenius ESR-750H wireless N router to an Asus RT-AC66U wireless AC router. The EnGenius router has been pretty good for me but basic and no support for other firmware. The Asus RT-AC66U not only has a number of added features and support for 802.11ac, it also doesn’t seem to be plagued with the port 32764 bug or the Linksys “TheMoon” virus that’s been going around on select Linksys models, but the Asus also has a number of firmware options that can be used with this router such as Merlin, Tomato, and DD-WRT.

I’ve used DD-WRT in the past with other routers and had great success and decided to go that route with my new AC66U router as well.

How to install DD-WRT on Asus RT-AC66U

To get started we need to download a few files first:

Now lets get started…

  1. I like to start with nothing attached to the router except for the machine I’ll be using to update the router so disconnect all other connections including WAN. Then log into the router Admin Panel (usually
  2. Enable Telnet by going to Advanced Settings > Administration > System > Enable Telnet and click on “Apply
    Enable Telnet on Asus RT-AC66U
  3. Open a command prompt, and type:

    Then enter your username and password for the router admin panel.

  4. Now clear NVRAM by typing:
    mtd-erase -d nvram
  5. Reboot the router now by typing:
  6. Once the router has rebooted log back into the admin panel (default login is admin/admin) and navigate to: Administration > Firmware Upgrade > New Firmware File and click on Choose File and select the .TRX file you downloaded (for me dd-wrt-25648-Asus_RT-AC66U.trx) and click on “Upload
    Upload DD-WRT firmwareNote: This step can take several minutes. Once completed you should see the DD-WRT page.
  7. Open a command prompt again and telnet into the router ( but this time for the username type in root for the username for the password use the one you chose when setting up the initial DD-WRT page.
  8. Again clear NVRAM by typing:
    erase nvram
  9. Reboot the router now by typing:

At this point it’s just a matter of setting up the router to your liking, such as username/password, wireless networks, security settings, etc.

How to get Port Forwarding working on DD-WRT

After upgrading my Asus RT-AC66U I noticed that for some reason port forwarding was not working. Apparently this is a known “bug” and is easily remedied by logging into the DD-WRT admin panel and navigating to: Administration > Commands then typing:

iptables -t nat -A POSTROUTING -j MASQUERADE

and click on “Save Firewall“.

dd-wrt port forwarding

Immediately port forwarding started working and no other bugs have been found so far. Glad to be back on DD-WRT and the new Asus router seems to be performing just fine!

UPDATED: Updated instructions using the latest DD-WRT build as of 12/18/2014. Also removed parts detailing installing a KONG build as development for the builds have been merged into the standard DD-WRT image.

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