This post will guide you through a LEDE Linksys WRT1900ACS installation. It’ll show you how to install LEDE on a WRT1900ACS fresh out of the box.

Update 2018-08-12: Since this post was published, the LEDE project and OpenWrt has merged. The LEDE project firmware is no longer maintained, but a new version of OpenWrt that contains everything from the LEDE firmware has been released. I’ve written a guide describing how to install OpenWrt on a Linksys WRT19000ACS router. You should use that guide instead of the information below.

Understand this: Always flash firmware using a wired connection, never via WiFi. Failure to adhere to this substantially increase the probability you will brick your router. I’ve only included instructions for flashing via an Ethernet below. If you chose to use a wireless connection instead, you’re on your own.

Warning: Flashing third party firmware will void your warranty. I will not be held responsible if anything goes wrong. Flashing a device’s firmware is always a risky operation, especially when you’re dealing with custom, unofficial firmware. By following this amateurish guide you understand that you might end up with a brick – a useless piece of hardware. Flashing a router with third party firmware isn’t a trivial thing to do, even with the help of this step-by-step guide. Make sure you read through the entire guide at least twice before you start so you get an overview of the steps.

With that out of the way, let’s get started.

1. Download the latest, stable LEDE release for the router. Download links can be found in this table. Make sure to download from the link in the “Firmware LEDE Install URL” columns, not the “Firmware LEDE Upgrade URL” column.
2. Power up the router.
3. Configure your Ethernet card with a static IP address of 192.168.1.2. How this is done varies from operating system to operating system. If you don’t know how, please consult The Internet.
4. Connect your computer and the router with an Ethernet cable. Connect to any of the 4 blue Ethernet ports on the back of the router. Don’t connect to the yellow one marked with “Internet”.
5. Open the Linksys router administration interface in a web browser. The default IP is 192.168.1.1 (link opens in a new tab/window).
6. Accept the terms and conditions, and click “Manual configuration”, and wait while the router tries to find an internet connection. Spoiler alert: It won’t find one.
7. After a while, the router will complain that the “Internet connection is down”. Click “Login”. The router will once again try to find an internet connection for about a minute. And it still won’t find one.
8. When the “Router password” prompt appears, log in with the password admin.
9. After you’ve logged in, take a long, hard look at the Linksys router administration interface. Soon it will be replaced by the sweet LEDE experience.
10. In the left-hand menu, click on “Connectivity”.
11. In the box “Manual”, click on “Choose file”, and select the LEDE firmware install package you download in step #1.
12. Click “Start”, then “Yes” on the warning prompt. The flashing process will start. Now is a good time to cross your fingers.
13. When the router is done flashing, the router will reboot. In my case, the flashing process took less than 30 seconds, but your mileage may vary. In any case, do not power off the router, or disconnect it from your computer. Wait. Be patient. Have a coffee. Then have a piece of pie.
14. When the router has rebooted, open the LEDE router administration interface in a web browser. The default IP is still 192.168.1.1 (link opens in a new tab/window).
15. Behold! Your Linksys WRT1900ACS now has LEDE installed! It might not be as sexy as the Linksys interface, but as we all know, real beauty comes from within.

Sources: Factory install: First-time installation of LEDE on a device, OpenWrt Techdata: Linksys WRT1900ACS v1.