High level outline of firmware upgrade process:
- Download the firmware
- Download Restoration Tool and N66U user manual
- Enter the router into Rescue Mode
- Prepare your computer
- Firmware upgrade
Asuswrt-Merlin does not support anymore these routers, so others continue doing that.
Asuswrt-Merlin Changelog ======================== 380.70 (8-Apr-2018) - NOTE: This will be the final 380.xx release for all models. The RT-N66U and RT-AC66U support will be dropped, and all other models have been migrated to the new gen branch, as of release 384.4. People who wish to keep getting updates for these two older models should look at the john9527 fork: https://bit.ly/2EV5Oat
Below is the link to the latest firmware, forked from Asuswrt-Merlin.
Download is shared on Microsoft OneDrive
Check @UpgradeMatrix.txt file which is available at the download folder. It describes migrations paths. I had Asuswrt-Merlin firmware, thus I had to use Restoration Tool to upload new firmware. I could not do that via Web Interface in my case.
And take an E build, which has latest software. The difference from L build is described at the end of matrix document.
Download Restoration Tool and N66U user manual
Download Restoration Tool from Asus RT-AC66U home page, latest is Version 220.127.116.11 https://dlcdnets.asus.com/pub/ASUS/wireless/RT-AC3200/Rescue_2000.zip?_ga=2.194002159.331485302.1567255072-1124498172.1566848698
Download user manual https://www.asus.com/us/Networking/RTN66U/HelpDesk_Manual/
Once all files are downloaded, enter router in the Rescue Mode.
It allows to upload new firmware from your computer. How to enter Rescue Mode, can be found in the user manual. But I’m pasting screenshot here.
Prepare your computer
Connect your computer to your router via cable. Connect to any of the four LAN ports. Other 3 LAN ports and 1 WAN port must be disconected from router. As well disconnect any USB device.
Your computer should have all other network adapters disabled except the LAN (cable) which will be connected to the router. As well disable proxy settings and dial-up connection if it is customized.
Set LAN settings on your computer
Restoration Tool must be started only after router is in rescue mode and connected to computer via specific IP address.
Whole process can take up to an hour, so be patient.
Open Restoration Tool, select the new firmware. Firmware file must be unzipped before.
Firmware being written
Once the firmware is uploaded wait a bit, check the power light and do the Factory Reset. Migration to new fork and upgrade is successful.