Asus RT-N66U

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=Links and Notes = =Links and Notes =
 +*[https://www.dd-wrt.com/wiki/index.php/Index:FAQ Frequently Asked Questions]
 +*[http://www.dd-wrt.com/phpBB2/viewtopic.php?t=51486 Peacock Announcement]: '''Required reading''' for DD-WRT on Broadcom routers!
 +
Primary forum threads Primary forum threads
* [http://www.dd-wrt.com/phpBB2/viewtopic.php?t=171783 One User's Guide] - A users guide for flashing Rt-N66u * [http://www.dd-wrt.com/phpBB2/viewtopic.php?t=171783 One User's Guide] - A users guide for flashing Rt-N66u
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* [http://www.smallnetbuilder.com/wireless/wireless-reviews/31687-asus-rt-n66u-dark-knight-dual-band-wireless-n900-gigabit-router-reviewed SmallNetBuilder Review] * [http://www.smallnetbuilder.com/wireless/wireless-reviews/31687-asus-rt-n66u-dark-knight-dual-band-wireless-n900-gigabit-router-reviewed SmallNetBuilder Review]
* [http://service.asus.com/demoui/RT-N66U/EN/index.html Asus Stock UI demo] * [http://service.asus.com/demoui/RT-N66U/EN/index.html Asus Stock UI demo]
- 
-==More Links== 
-*[https://www.dd-wrt.com/wiki/index.php/Index:FAQ Frequently Asked Questions] 
-*[http://www.dd-wrt.com/phpBB2/viewtopic.php?t=51486 Peacock Announcement]: '''Required reading''' for DD-WRT on Broadcom routers! 
[[Category:Asus guides]] [[Category:Asus guides]]

Revision as of 14:16, 23 January 2018

Contents

Hardware

This 'Dark Night' presents significant risk (bricking) that requires careful adherence to the installation process. The NVRAM issue has been resolved, however, knowing what builds can be used must be understood well.

Specifications

  • Dual Band Router - 2.4GHz and 5GHz bands
  • Wireless controller Broadcom BCM4331
  • MIMO 3x3 on both frequencies (see Forum, BrainSlayer)
  • Gigabit LAN and WAN switching
  • 2x USB 2.0 connectors
  • CPU Broadcom 4706 @ 600MHz
  • 256MB RAM
  • 32MB FlashRAM
  • Built-in Micro SDHC socket
  • Power supply: DC Output, 19 V, max. 1.58 A current (=> max 30W)
  • Serial header: 8, n, 1, no flow control, 115200.

Reset button for Recovery

Pressing the Reset button at powerup will put the N66U into recovery mode.

  • Press and hold the reset button while plugging in the power, and keep pressing the reset button for about ten seconds until the power led is blinking slowly, then release the reset button. The router is now in recovery mode: go to 192.168.1.1.

WPS button to Clear NVRAM

Pressing the Red WPS button at powerup will reset (clear NVRAM) to default settings.

  • Press and hold the WPS button while plugging in the power, and keep pressing the WPS button for about ten seconds, then release the WPS button. All settings have now been wiped, and default settings will be used.

NVRAM issue

IMPORTANT: DO NOT USE K2.6 builds if using CFE v1.0.1.3 (64K nvram) or NEWER!!!
At launch, the RT-N66U was limited to 32k nvram. However, CFE (bootloader) version 1.0.1.3 added 64k nvram support around April 2013, but was not compatible with DD-WRT firmware at that time. For details, see these forum links to historical nvram and 64K implemention discussions: Fractal comments and "RT-N66 CFE Thread"

This was resolved with DD-WRT K3X builds (kernel 3.x) which extended nvram to 64k, and can be used for any CFE version. It was eventually extended to 256k.
More historical info: http://charleswilkinson.co.uk/2012/12/22/dd-wrt-on-the-asus-rt-n66u-with-64k-cfe/
For newer CFE version updates and procedures see here: SNB Forums

CFE Version (or Update)

AsusWRT-Merlin can be installed to enable telnet and check the CFE version, and still be flashed directly to DD.

  • In nvram: nvram get bl_version
  • CFE partition: strings /dev/mtd0ro | grep bl_ver

K3.X Builds

  • Read the New Build threads on the forums, such as this.
  • Find new builds in the Broadcom_K3X build folder.
  • 8-Mar-2015: 26138 is a good (recommended) build for the RT-N66U:
    1. Big
    2. Mega

K2.6 Builds

USB (and thus MMC) also does not work in K2.6 builds. USB devices cause a kernel panic: see SVN ticket. Use a K3.x build (see above), which also works around the NVRAM issue.

DD-WRT Alternatives

User Merlin implemented a solution in mid-2012 to extend the original 32k NVRAM CFE to ~60k NVRAM in firmware.

TomatoUSB Shibby also implemented a 64k NVRAM solution for 32K NVRAM CFE in 2012.

Historical Build Information

  • 25-May-2013: With the new experimental K3.X Broadcom builds, the CFE version is irrelevant. DD-WRT detects it automatically to extend 32KB NVRAM to 64KB. Which Image you have to flash, depends on your previous Image (Stock, Merlin, DD-WRT K2.6).
  • For DD-WRT K2.6: It depends how much NVRAM ( 32KB / 64KB ) you currently have.
    For 32KB, flash 26138 mega.
  • If you are already on a custom 64K Build like Fractal or Kong with CFE 1.0.1.3, you need to flash 26138 mega nv64k. Since K2.6 Builds have an embedded check, you need to use those special nvXXk trailed images. On K3.X this check has been removed and you can simply upgrade from a previous K3.X.
  • 8-Mar-2015: Kong 22000++ is a good (recommended) build for the RT-N66U with 64K CFE
    with fix for the serious Heartbleed vulnerability.
  • 9-Apr-2013: It seems more recently manufactured units come pre-loaded with the 64K v1.0.1.3 CFE and so are not compatible with standard DD-WRT builds. Flashing a K2.6 DD-WRT build on these devices will result in a brick.
  • 26-Jan-2013: Current versions of DD-WRT can quickly run out of 32k nvram.
  • Build 18946 fixes the WAN port issue.

Installation Instructions

For recommended builds, read the Peacock Announcement, New Build, and model-specific threads.

Principle steps

For builds and more information, see here: Where do I download firmware?.
IMPORTANT: DO NOT USE K2.6 builds if using CFE v1.0.1.3 (64K nvram) or NEWER

  • Older CFE (32K nvram) can use K2.6: see the above K2.6 and K3.X sections for details
  1. Reset or select Factory Default settings.
  2. Install the trailed ASUS RT-N66U version of DD-WRT (file name ends in .trx) using either the Web GUI method or the Recover Utility method. Both methods are described below
  3. Reset again
  4. "Upgrade" to your final version of DD-WRT (filename ends in .bin) using Web GUI or Recovery Utility
  5. Reset again

IMPORTANT: Reset to clear NVRAM (or Admin->Factory Default settings) BEFORE and AFTER firmware upload.

Upload Firmware via Web GUI

  1. Reset or select Factory Default settings.
  2. Upload the .trx file using the stock web GUI. See Where do I download firmware? for links. See the build threads on the forums for recommendations.
  3. When complete, wait until the router reboots itself, which can take at least 10 minutes. You want both ping response and web gui response to know that the router is fully rebooted.
  4. Hard reset or select Factory Default settings. Wait for the router to reboot itself!!! May take 10 minutes or more

Upload Firmware via Recovery Utility

  1. Set your computer to a static IP (e.g. 192.168.1.12), subnet 255.255.255.0, default gateway 192.168.1.1
  2. Put router into recovery mode by holding down the reset button while powering up the router, wait until the power led is blinking slowly, then release the reset button.
  3. In the Asus Recover utility Access the router’s built in recovery mode by issuing 192.168.1.1 in browser field.
  4. Flash the initial DD-WRT trailed build (with N66U in the name) and upload.
  5. When complete, wait until the router reboots itself, which can take at least 10 minutes.
  6. Enter recovery mode again and flash the final DD-WRT build (big or mega with N66U in the name).
  7. When complete, wait until the router reboots itself again.
  8. Enter recovery mode again and select to Restore defaults NVRAM values
  9. Wait until the router reboots itself, which can take at least 10 minutes.
  10. Now you should be able to access the DD-WRT GUI at 192.168.1.1 to set a password.

Switching from Tomato

  1. Download the latest K3.x mega build. See Where do I download firmware? for links. See the build threads on the forums for recommendations.
  2. Navigate to the Tomato firmware update page
    • Administration > Upgrade
  3. Upload the firmware you downloaded in step 1
  4. The router will reset several times and change its IP address to the default one (192.168.1.1).
  5. Navigate to http://192.168.1.1/Factory_Defaults.asp
    • The login credentials have been reset to the default dd-wrt username/password (root/admin)
  6. Set "Restore Factory Defaults" to yes and click "Apply Settings".
Note: Many settings will carry over from Tomato to DD-WRT, but it's highly advisable to reset to factory defaults after flashing, or you risk undesired behavior and instability.

Upgrade to newer DD-WRT

  • Clear settings (Clear NVRAM)
  • Use the DD-WRT web GUI : Administration -> Firmware upgrade
  • Clear settings (Clear NVRAM)
  • svn24461 BRICKS RT-N66U. Recover possible through mini CFE webinterface.

Revert to original ASUS firmware

  • Download firmware from ASUS web site
  • Reset to Factory Default Settings or clear NVRAM
  • Use the DD-WRT web gui: Administration -> Firmware upgrade
  • Reset to Factory Default Settings or clear NVRAM

Install an internal MicroSD card

Important note: USB (and thus MMC) is not supported on K2.6 builds - it causes a kernel panic. However it is working on K3.x builds. See SVN ticket

  1. Open the case
    • Unscrew the four screws at the bottom
    • Then you want to release the plastic clips that holds the top and bottom parts together.
    • Pry the bottom case outward, which has the male clips.
    • For future access, it is recommended to either snip off the female "U" clips on the top cover, or round off the square edges on the male part of the clip with a nail file.
  2. Install MicroSD card
  3. Make use of the MicroSD card

In addition to the NAS features of DD-WRT, you can use the extra space to install Optware or Entware-3X (recommended over Optware).

Without MMC on K2.6 builds, Optware can't be installed. Use K3.x builds: OTRW Take 2

Performance

Test Description                                RT-N66U
WAN - LAN	                                       732 Mbps
LAN - WAN                                         729 Mbps
Total Simultaneous                            810 Mbps
Maximum Simultaneous Connections   34,925
Firmware Version                                3.1.0.3.90  (stock firmware number)

Sources and testing methods

Overclocking

Overclocking works since CFE 1.0.1.3, while underclocking worked prior to that. Overclocking may cause instability, or services (like QoS) to behave unpredictably

  • Recommended to improve cooling or ventilation when overclocking
  • One report of QoS degradation at 632Mhz with K3.X big r27360 (06/18/15)

Links and Notes

Primary forum threads

Additional forum threads