From DD-WRT Wiki
 Hardware Information
|CPU Speed||300 MHz|
|Flash ROM||8 MB|
|Radio||2x 2.4 GHz or 5 GHz|
|WLAN Max Speed||300 mbps|
|MIMO Config||2T x 2R|
|Switch||4x 10/100 LAN + 1 10/100 WAN|
 Flashing instructions for the E2500
After using the trailed build file for the initial flash (the firmware file that has the name that ends with "mini-e2500.bin") only use nv60k builds to upgrade with or you will brick your unit!
- Read the Peacock Announcement carefully.
- Disconnect all cables and wireless clients.
- Do a 30/30/30 reset on router using the small reset button on the bottom, not back, of the unit.
- Connect 1 Lan cable to pc doing the flash.
- Log into Linkysys Web Interface Firmware Upgrade page at 192.168.1.1, click on the "continue with an open and unsecured network", put "root" for your username and "admin" for your password, go to the administration/firmware Upgrade tab, and flash the firmware E2500 Trailed Initial Flash Build MAKE SURE THE FIRMWARE YOU ARE FLASHING HAS E2500 IN THE NAME!
- Wait 5 minutes to assure flash integrity.
- Power cycle by unplugging E2500 for 10 seconds.
- Plug E2500 back in and wait about 3 minutes until it finishes booting.
- Do a 30/30/30 reset using the small button on the bottom, not back, of the unit on the router.
- Wait 3 minutes and log into web interface.
- You are done.
- After the initial flash - should you want to flash to a build with more features you can use a k2.6 nv60k BIG or mega build or any of the other build flavors that are of your liking for features.
 Flashing on hardware v2
The initial flash with the trailed build file works the same with the v2 hardware revision of the router as it does with the v1 revision, despite the trailed build being labeled for use with the v1 revision in the dd-wrt router database. There is no difference with using dd-wrt on the v2 version of the router versus the v1 version.
 Flashing Version 3
This is highly experimental, but Fractal has apparently ported an unofficial 23569 version of dd-wrt for this router. Follow the instructions above and use the build from this thread:
There are threads that indicate that you cannot flash back to stock Linksys firmware using the webgui with this router, and will have to use tftp to flash oem firmware.
 Build information
As noted in bold at the beginning of the flashing instructions, only use builds with nv60k in the name for upgrading - otherwise follow the initial flash instructions above if you are going from stock to dd-wrt, any other builds for upgrading an exsisting dd-wrt install without nv60k in the name will brick your router! This unit was supported with build 18946 or greater, for the v1 and v2 hardware, this means you cannot use a build with a number lesser than 18946, also avoid the test builds within the E2500 forum thread and the builds linked in the dd-wrt router database as they are known to cause a reboot loop. For the safest results, use builds that are linked within this wiki.
To find the latest builds, you can browse the DD-WRT file server and look for the broadcom_K26 folder, in there is the appropriate for your unit. Be aware that these are beta test builds and should be used with caution!
 Known limitations
The 5 GHz radio does not function on this device when running dd-wrt v24. This is because the 5 GHz radio functions off the USB bus (not the PCI bus). This is a problem because a driver has yet to be ported for the 5 GHz radio on the USB bus for any dd-wrt device.
If you get an "upgrade failed" message, and are sure you followed the instructions exactly, first double check you are not trying to flash v1 firmware on a version 3 router, and then try a different browser.
 Reverting to stock firmware
It has been asked about: "how do i revert back to stock firmware?" and the answer is download the stock firmware image from the manufacturer's website, reset the router back to defaults using a 30-30-30 hard reset, then flash the stock image from within the dd-wrt webgui. After 5 minutes it should finish, you will then need to do another 30-30-30 reset and then access the stock webgui @ 192.168.1.1
The v3 model might require that you use tftp. See note 11 of the peacock announcement for further guidance.