[spuriousoffspring]

First and most important: never do a ‘Hard Reset’ aka 30/30/30!. It's unnecessary and you can harm your router.

*The ‘Hard Reset’ applies only to much older routers. If the router you are installing or upgrading DD-WRT on is a WRT1200, WRT1900, WRT3200 or a WRT32X a simple hold of the reset button (located on the back of the router) for 20 seconds while router is powered ON will clear NVRAM and restore router to defaults.

*A 'normal reset' is not always necessary unless there is a problem, but some do it as a preventative measure before and/or after installing or upgrading.

Note: NVRAM stands for ‘Non-Volatile Random Access Memory. It is where the router’s configuration and settings (both Partitions) are stored.

There are two other simple methods of clearing NVRAM and returning to default status.
1. In the DD-WRT GUI under the Administration Tab – Factory Defaults Sub-Tab.
• If you are upgrading from within the DD-WRT GUI you can also select a reset after upgrade is completed. Located in Administration Tab – Firmware Upgrade Sub Tab.
2. Telnet or SSH Commands:
erase nvram && reboot - Builds from 18 Apr 2018 or older (35681 and prior)
nvram erase && reboot - For builds after 18 Apr 2018 (35770 and later)

Note: Telnet Client can be used on a Windows PC, but may need to be added on. Here's how: Control Panel – Add Programs – Turn Windows Features On or Off – Telnet Client (Check Box)

Instructions for Telnet on a Windows 7 PC:
http://www.wikihow.com/Activate-Telnet-in-Windows-7

PuTTY is an easy to use & free Telnet & SSH Client that can be downloaded here:
http://www.putty.org/

First Time DD-WRT Firmware Installation or Upgrade (WRT1200AC, WRT1900AC, WR1900ACS, WRT3200ACM)

For WRT32X-specific Information, please read the following:

• WRT32X DD-WRT Installation Procedure
  
• [SOLVED] WRT32X back to stock Firmware

NOTE: Initial flash should be done with 01-07-2018-r34411 due to Linksys OEM partition size restrictions.

The first thing you will need (obviously!) is the DD-WRT Firmware File.
The newest Firmware Builds can always be found here:
ftp://ftp.dd-wrt.com/betas/
or here:
https://download1.dd-wrt.com/dd-wrtv2/downloads/betas/
or here:
http://www.dd-wrt.com/site/support/other-downloads
*Betas - Current Year

Before downloading DD-WRT Firmware (from any of the above sites) it is a very good idea to first clear your Browser History / Cookies.
Sometimes the Firmware file can become corrupted during initial download.

Before you Install Firmware: These are Beta Firmware Versions. There is always the possibility of 'bugs'. By installing any one of these builds you have become a Beta Tester.
If this isn't your preference then I highly suggest you wait and monitor the Forum.

Each build will have it's own Forum Thread (Topic) where other Forum members post updates on stability and anything else pertaining to that particular build.
Also, if you are looking for a recommended build here is where you will find advice.
The newest Firmware Build is generally the recommended one.

There is no Official Change Log. However, information about Tickets and Changesets can be found here:
http://svn.dd-wrt.com/timeline

*If you have decided to try a new build then please update the Forum Thread with your own observations. This will help others to decide and it will help the developers to monitor for any issues.

Note: I recommend creating two Download Folders and naming them DD-WRT Firmware and DD-WRT Backups (or your personal preference) and in those folders creating Sub-Folders labeling each with the date and Firmware Version Number. This will help keep you organized and prevent the wrong Firmware or Backup from being uploaded.

Important: Backups from one version are NOT recommended to restore another version!

Find your router in the list by Model Number & Hardware Version.
For each router in the list there will always be two BIN files:
factory to dd-wrt
dd-wrt webflash

*Please pay close attention to this:

The factory to dd-wrt is for installing DD-WRT from the Linksys GUI. This file will be used under two circumstances.
1. You are installing DD-WRT for the first time.
2. You have switched back to opposite partition and you have the Linksys Stock Firmware on that partition.

The dd-wrt webflash is for upgrading a current DD-WRT installation. This file will result in the following circumstances.
1. A new version of DD-WRT will be installed on the opposite & inactive partition.
2. The previous DD-WRT version will be left on what is now the inactive partition (after reboot).
3. All settings and configuration will be kept and applied to new version (unless a reset is selected in Firmware Upgrade Sub-Tab).

Note: It’s only one file per Install / Upgrade. If you use the ‘factory to dd-wrt’ file followed by the ‘dd-wrt webflash’ file you will have installed the same version of DD-WRT on BOTH partitions and overwritten the Linksys OEM Firmware.

Important: Never Install / Upgrade via wireless. Always use a LAN Cable!

Instructions for upgrading Firmware from Linksys GUI can be found here:
Manually upgrading a Linksys Smart WiFi Router's firmware

*It will be up to you to decide if you want to return to the Linksys OEM Firmware and Install each new version of DD-WRT over the previous and thus keeping the Linksys OEM Firmware on one partition at all times.
This will make trying out other Third-Party Firmware much easier as you must Install from Linksys GUI. This includes OpenWRT, LEDE, Tomato, Gargoyle, Merlin, etc.

I find it EASIER to just upgrade and keep configuration intact.

This isn’t as important as it once was as the newer DD-WRT versions have the ability to return to Linksys OEM. Simply upload the Linksys Stock Firmware from DD-WRT GUI Administration Tab – Firmware Upgrade Sub-Tab. (Same as you would upgrade DD-WRT)

Note: This feature was added to 07-08-2017-r32597 and every subsequent build thereafter.
http://svn.dd-wrt.com/changeset/32438

Trick to Upgrade DD-WRT Firmware without losing current configuration or the need to return to Stock Firmware:

Using Telnet/SSH and the ubootenv set boot_part command (described below) it is possible to upgrade to a newer version of DD-WRT without the need to manually switch back to Stock Firmware Partition. All previously configured settings will remain intact.

1. Use the ubootenv get boot_part command to learn the current Partition in use.
2. Use the ubootenv set boot_part (1 or 2 – the opposite number returned in Step 1) command.
3. DO NOT REBOOT
4. In DD-WRT GUI – Administration Tab – Firmware Upgrade Sub Tab: Upload the new ’dd-wrt webflash.bin’ file for your Router & Hardware Version. MAKE SURE THAT NO RESET IS SELECTED.
5. After Firmware Upgrade is finished the Router will automatically reboot.

*You should now have the new DD-WRT upgrade on the current Partition and OEM Firmware will still be intact on opposite partition.

The preceding was provided by an unknown author on this Forum. Whomever you are, thank you! Also, thank you to @myersw for saving & providing a copy and to @gainestr for testing.

Upgrading from within Linksys OEM Firmware


The Linksys OEM Firmware for your router can be downloaded from the Linksys Support Website here:
https://www.linksys.com/us/support/

*Just enter your router’s Model Number and make sure to select the correct Hardware Version.

Note: The time it takes for Firmware to upload and router to reboot is approximately 90 seconds. For a first-time installation, the page may freeze and it may be necessary to close your browser, open again and re-navigate to default router IP Address.

Linksys Default Router IP Address: 192.168.1.1
DD-WRT Default User Name: root
DD-WRT Default Password: admin

A list of Linksys OEM Firmware default IP Addresses, User Names & Passwords can be found here:
https://www.lifewire.com/linksys-default-password-list-2619153

Important: Telnet / SSH User Name will always be: root
*Regardless of what you have changed it to in the Linksys or DD-WRT GUI.
Telnet / SSH Password will be: the password you have selected in Administration Tab – Management Sub-Tab.
*If you have not changed it - then it will be the default: admin

What to do If something goes wrong. Don’t panic! These WRT routers are just about un-brickable. The Dual-Partition feature makes recovery easy.
First try rebooting. Remember 90% of problems with ALL electronics can be solved be a simple restart.
Second, try a different Browser. At one time or another Microsoft Edge, Internet Explorer, Safari, Google Chrome and Mozilla Firefox have all experienced issues with the DD-WRT GUI.

If either of these do not work the next step is to return to the previous Firmware on the opposite partition and try again.

There are two simple ways of switching partitions:
1. Telnet or SSH Command to learn what partition is currently in use
WRT1200, WRT1900AC, WRT1900ACS & WRT3200ACM: ubootenv get boot_part
WRT32X & WRT32XB: fw_printenv boot_part
*The last line will be a # 1 or 2. This is the partition currently in use.

Telnet or SSH Command to switch to opposite / inactive partition
WRT1200, WRT1900AC, WRT1900ACS & WRT3200ACM: ubootenv set boot_part [1 or 2]*
WRT32X & WRT32XB: fw_setenv boot_part [1 or 2]*
*Use the number not in use.

2. Power Cycle the router three times.
Using the router’s power switch – turn OFF then turn back ON.
Wait 2 seconds then turn OFF.
Turn back ON.
Wait 2 seconds then turn OFF.
Turn back ON.
Router should have booted into opposite partition.

Note: For the purposes of keeping this as short and simple as possible, other recovery methods will not be discussed, but some helpful links will be provided at the conclusion.


DD-WRT Initial Setup and Configuration

*Basic Setup and Configuration ONLY. Links to more advanced setup tutorials below.

The first thing to do is setup a router User Name & Password in the Administration Tab – Management Sub-Tab. These are the credentials you will use to log into the DD-WRT GUI to view status and make changes.

*Also in this section: Router GUI Style – Customize the look of the DD-WRT Control Panel

Next, setup the router’s time. Setup Tab – Basic Setup Sub-Tab. 'Enable' NTP Client, select the appropriate Time Zone and in the Server/IP block: Leave Blank
*This should automatically choose the closest NTP Time Server to you.

A list of specific NTP Time Servers can be found here:
https://www.dd-wrt.com/wiki/index.php/Network_Time_Protocol

Next, setup Wireless Settings & Security. Wireless Tab – Wireless Security Sub-Tab. From the ‘Security Mode’ drop-down menu select WPA2 Personal and in ‘WPA Algorithms’ menu choose AES.
In ‘Shared Key’ enter your choice for a WiFi Password.

*This will be the password you enter on your wireless devices to connect to WiFi. MAKE IT A GOOD ONE!

Note: Dual-Band Routers do this for both bands: ath0(wlan0) and ath1(wlan1).

Note: The WRT3200ACM Firmware has a third WLAN (ath2(wlan2)). While some have had limited success enabling it it is recommended that it be Disabled. It was intended for DFS Radar Detection.
*This does not give you a Tri-Band Router.
More information can be found here:
DD-WRT support for WRT3200ACM?? pg3
An explanation of DFS Radar Detection can be found here:
http://wifi-insider.com/wlan/dfs.htm

Next, Wireless Network configuration. Wireless Tab – Basic Settings Sub-Tab. Here is where you enter you Wireless Network Name (SSID) and much more. *For the rest please see links below.


Definitions:

GUI Graphic User Interface. This is the DD-WRT Control Panel.
NVRAM Non-Volatile Random-Access Memory. See above description.
OEM Original Equipment Manufacturer
NTP Network Time Protocol
SSID Set Service Identifier
TFTP Trivial File Transfer Protocol
BRICKED Router is toast! Unrecoverable. Return to the store & pray they accept a return or keep for spare parts.
SOFT-BRICKED Router is almost toast. Only means of recovery is a USB to TTL Serial Cable


References and other Helpful Links

• DD-WRT Forum - Basic DD-WRT Install FAQ for WRT1900AC?
  
• DD-WRT Forum - Linksys WRT1900AC/Marvell support
  
• DD-WRT Wiki – Installation (While much of the info is out-of-date, most is still very useful)
  
• DD-WRT Wiki - Tutorials (While much of the info is out-of-date, most is still very useful)
  
• DD-WRT Wiki – QCA Wireless Settings
  
• DD-WRT Wiki – Advanced Wireless Settings
  
• DD-WRT Wiki - Logging with DD-WRT
  
• NTP Official Website – ntp.org
  
• Linksys TFTP Instructions and Download can be found here:
  Upgrading the router’s firmware using the TFTP utility (web archive)
  
• More information on Serial Cable recovery can be found here:
  https://github.com/Chadster766/McDebian/wiki/1.-USB-to-TTL-Serial-Connection
  
• inSSIDer 4 – Last free version can be found here:
  http://www.dd-wrt.com/phpBB2/viewtopic.php?t=310493&start=75
  
• WiFi Commander App – Windows Store. More info here:
  http://wificommander.com/

*The Linksys TFTP Utility is an alternative way of installing / upgrading Firmware. Useful when there is a problem. More info can be found on the DD-WRT Wiki here:
https://www.dd-wrt.com/wiki/index.php/TFTP_flash

*While inSSIDer is free (do not update after installation) the WiFi Commander App has a small fee to download from the Windows Store.
* Both are great for scanning surrounding Wireless Networks. Essential for proper WiFi Channel adjustments.


Acknowledgements:

Brainslayer – (Obviously!) For great Firmware that keeps getting better.
Kong – (Also Obviously!) For all the testing that provided very reliable Firmware for a long time.
jsebean - For the ‘Basic DD-WRT Install FAQ for WRT1900AC?’ where much of the information in this post has come from.
myersw – Many posts that also provided much of the above information. Also, THANK YOU for providing inSSIDer 4!
All the many, many other Forum members who have asked and answered questions.

I have learned an incredible amount from this Forum and I look forward to more.

P.S. When posting on the Forum please always include your router’s (or other equipment’s) Model Number & Hardware Version.
Better yet add it to a signature so that it will be automatically included with every post.
This will help others who have the same equipment.

[1mn0tjack]

So if I understand correctly,and say I accidentally put ddwrt on both partitions, I can revert to the Linksys firmware by installing the firmware update from Linksys using the ddwrt firmware upgrade tab.

I have tried that, and it seemingly isn't working.

[giles02134]

Wish I'd stumbled onto this thread earlier on--would have saved me a lot of trouble.

I do have a question: I understand that on my Linksys WRT1900ACSv2 if I perform an upgrade from within DD-WRT, the newer version will get written to the other partition, blowing away the factory firmware.

I've never performed an upgrade before. Are settings preserved when one is going from one release to the next realease? EXAMPLE: I'm at build 3342. If I bump up to the next release from within DD-WRT(blowing away the Linksys firmware), will my settings be preserved?

Alternately, were I to upgrade from within the Linksys firmware from DD-WRT 3342 to 3345, would the settings backup from 3342 correctly restore to 3345?

Thanks!

[spuriousoffspring]

I will post a reply for you in a new Topic.

[Kalsta]

Great write up, and very timely with the KRACK patches currently being released.

Question regarding flashing factory firmware, after upgrading DD-WRT (resulting in DD-WRT on both partitions), which partition should you flash the factory firmware on - the newly upgraded partition, or the previous non-upgraded partition?

I'm just wondering if all installs/upgrades are written to the inactive partition or if this is a DD-WRT only thing.

Cheers,

Kal

[spuriousoffspring]

[Kalsta]

[Zrullac]

I just opened the box on my new WRT3200ACM. I connected it directly to my laptop and navigated to 192.168.1.1. The Linksys auto setup routine started. I tried to find a way to cancel that and go directly to the GUI so I could flash the latest build. I can't get past the setup routine. Do I have to complete the Linksys setup routine before I install the factory to DD-Wrt firmware?

[spuriousoffspring]

You don't have to, but you might as well let it finish before you switch to DD-WRT.
You'll have less 'down time' if you need to revert back to stock for some reason.

[Zrullac]

Thanks.

[Zrullac]

Finally got through the Linksys setup routine. Starting to flash DD_WRT firmware build r33986 factory to DD-Wrt bin. Used the Linksys GUI to choose file. Clicked Start and got the following message: "Unrecognized file name. The file you selected does not appear to match your router model. Installing this may cause the router to stop functioning properly. Are you sure you want to continue?" I assume I got this message because this isn't a Linksys file name. Should I proceed?

[spuriousoffspring]

Yes, proceed. That warning is just cause the DD-WRT firmware is a .bin file extension.
If you want you can change it to .img and that will clear the error, but it's not necessary.

[Zrullac]

Followed your instructions. Router rebooted with no problem. DD-WRT control panel came up the first time, no need to reboot. Changed user name and password first, then followed your setup recommendations. Now next step is to figure out how to configure my Arris NVG599 modem form AT&T for IP pass-through.

[2tone73]

First up, great write up. The tips about using telnet to swap partitions saved my bacon. I thought I'd done something wrong and reinstalled several times with what I thought was a bad or partial install. I got a mostly blank screen with some login/password boxes that don't work.

On a whim, I loaded the page in Safari instead of Chrome (I'd read not to use Firefox and thought Chrome was safest) and voila!

So, on a Mac at least, do not use Chrome, use Safari.

Fellow noobs, take note!

[spuriousoffspring]

Try clearing your history on Chrome. I've had issues with Edge, Internet Explorer, Chrome and Safari (mobile) at one point or another.
Clearing history / cookies usually resolved it. Sometimes a restart is also necessary.