DD-WRT on Linksys WRT1900ACS v2-Upgrade-Downgrade-Revert to stock 2018-01-09
dd-wrtwrt1900acs v2

Linksys WRT1900ACS v2 has a very nice feature. It has two boot sectors. That makes the upgrading/downgrading of DD-WRT a little bit more complicated (that is if you want to keep the stock firmware in one sector) but makes reverting to stock very easy.

Following the method below you will always have one boot sector with DD-WRT which you can upgrade/downgrade and another boot sector with the stock firmware.

Keep in mind that if you don’t use the method below to upgrade/downgrade DD-WRT after it’s initial installation, you will end up having DD-WRT in both boot sectors (one sector with the initial DD-WRT version and the other sector with the one you upgraded/downgraded)

Upgrading/Downgrading DD-WRT on Linksys WRT1900ACS v2

Assuming you have already installed DD-WRT as described in the install section here, you can now upgrade or downgrade your DD-WRT version. Head to the DD-WRT ftp area and fetch your preferred version. Please not that you need to select the ddwrt-linksys-wrt1900acsv2-webflash.bin image (the factory-to-ddwrt.bin image is only used installing DD-WRT from stock).

Open an ssh connection to DD-WRT and print the currently booting sector

root@DD-WRT:~# ubootenv get boot_part
a_pEnv->crc = 89f37dad
crc32 = 89f37dad
2
root@DD-WRT:~#

So from the above we get that the booting sector is 2. We need to change the booting sector to 1.

root@DD-WRT:~# ubootenv set boot_part 1
a_pEnv->crc = 89f37dad
crc32 = 89f37dad
root@DD-WRT:~# ubootenv get boot_part
a_pEnv->crc = 566f5985
crc32 = 566f5985
1

 

Login to the DD-WRT GUI

Navigate to Administration–>Firmware Upgrade

Select the firmware image you downloaded and make sure Don’t Reset after flashing is selected

Click Upgrade

Wait for the router to upgrade and reboot and login again

Revert to stock firmware on Linksys WRT1900ACS v2

Reverting to stock if the above method is followed is as easy as changing the boot sector and rebooting the router.

Open an ssh connection to DD-WRT and print the currently booting sector

root@DD-WRT:~# ubootenv get boot_part
a_pEnv->crc = 89f37dad
crc32 = 89f37dad
2
root@DD-WRT:~#

So from the above we get that the booting sector is 2. We need to change the booting sector to 1.

root@DD-WRT:~# ubootenv set boot_part 1
a_pEnv->crc = 89f37dad
crc32 = 89f37dad
root@DD-WRT:~# ubootenv get boot_part
a_pEnv->crc = 566f5985
crc32 = 566f5985
1

 

Login to the DD-WRT GUI

Navigate to Administration–>Management

Scroll down to the end of the page

Click on Reboot Router

Wait for the router to reboot. Your rooter is rebooted to the stock firmware. Use the default settings of the stock firmware to connect to your router.