From DD-WRT Wiki
 Important Notes
Only version 1 is supported. Versions 2 & 3 are not yet supported.
Use only K2.6 builds with nv64k in the name.
dd-wrt.v24-21676_NEWD-2_K2.6_mini-nv64k (and big) appear to be the latest build with working wireless.
Please note build size limits listed in peacock annnouncement. Some Mega builds might be too big
Recently (2014/05/31) tried flashing beyond this, to builds like dd-wrt.v24-24160_NEWD-2_K3.x_mega-WNDR3400.chk and dd-wrt.v24-23838_NEWD-2_K3.x_mega-nv64k.bin and met with failure (brick, had to pin-reset). So these instructions are current!
Read Peacock topic (at top of Broadcom Forum). Read it all. Carefully.
 Hardware Specs
|CPU Speed||480 MHz|
|Flash ROM||8 MB|
|Radios||2.4 GHz and 5 GHz|
|WLAN Max Speed||300 mbps on 2.4Ghz and 300mbps on 5Ghz|
|Switch||4x 100 LAN + 1x 100 WAN|
|USB||1x USB 2.0|
 DD-WRT Installation
- There are two versions of this router with corresponding initial flash mini firmware. One is for Netgear branded routers and the other is for Cablevision routers.
- Do a factory reset (recessed button in the back), and upgrade with the appropriate mini firmware above. If it complains about downgrading, just Allow.
- To gain functionality of the usb port, upgrade to the big version or the mega version after flashing the mini version above.
- 30-30-30 reset router (as described in Peacock).
 Build Notes
- This is a good build for this router.
- Upgrading to 21676 Big will brick this router! Use 21676 Mega instead.
- This is otherwise a very good build for this router.
This router can be "bricked" (rendered inoperable) by flashing the wrong firmware; by not following the correct flashing procedure (in Peacock); or by flashing a bad build like 21676 Big.
 Factory method
 Recovery mode method
This method, which works on the WNDR3800, may also work on the WNDR3400v1.
 Pin short method
- Timing of the pin shorting is tricky -- power on, wait for the lights to flash, then try shorting a few times until the power light starts flashing steadily.
- Next use tftp2 (with no password) to flash factory firmware.
- After the flash, wait at least five minutes after the router boots up and the power light becomes steady green before resetting the router.
Here is another overview of the process for the WNDR3400 http://stevejenkins.com/blog/2014/01/how-to-unbrick-a-netgear-wndr3400-n600-router-after-a-bad-dd-wrt-flash
 Revert to Factory Firmware
- Download official Netgear firmware
- Reset DD-WRT (recessed button in the back)
- Enable telnet under services
- Telnet to router (192.168.1.1)
- Issue the command "mtd erase linux" & wait ~3 mins
- tftp the official firmware to the router
- tftp for windows  enter router ip, leave password blank, select official firmware file
- 30-30-30 reset router (as described in Peacock)