How To Install OpenWrt on a Linksys WRT1900ACS

This post will guide you through an OpenWrt Linksys WRT1900ACS installation. It’ll show you how to install OpenWrt on a WRT1900ACS running the stock Linksys firmware.

This summer, the OpenWrt project released OpenWrt 18.06.0. This is the first released since LEDE and OpenWrt merged, and what a nice release it is. The changelog is overflowing with all kinds of changes you want. This guide is based on a WRT1900ACS running version, so your mileage may vary. If you have a router with another version of the Linksys firmware, the user interface might look a little different, but the guide should still provide you with enough information to get OpenWrt installed.

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 cable 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.

Let’s Install OpenWrt on Your Linksys WRT1900ACS!

  1. Download the latest, stable OpenWrt release for the router. Download links can be found in this table. Make sure to download from the link in the “Firmware OpenWrt Install URL” columns, not the “Firmware OpenWrt Upgrade URL” column.
  2. Power up the router.
  3. Configure your Ethernet card with a static IP address of 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 (link opens in a new tab/window).
  6. The router will complain that there is no internet connection. This is completely natural, since there is none.
  7. Log in with the password admin.
  8. After you’ve logged in, take a long, hard look at the Linksys router administration interface. Soon it will be replaced by the sweet OpenWrt experience.
  9. In the left-hand menu, click on “Connectivity”.
  10. In the box “Manual”, click on “Choose file”, and select the OpenWrt firmware install package you download in step #1.
  11. Click “Start”, then “Yes” on the warning prompt. The flashing process will start. Now is a good time to cross your fingers.
  12. 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.
  13. If you see a button labeled “reboot”, click that.
  14. When the router has rebooted, open the OpenWrt router administration interface in a web browser. The default IP is still (link opens in a new tab/window).
  15. Behold! Your Linksys WRT1900ACS now has OpenWrt installed! It might not be as sexy as the Linksys interface, but as we all know, real beauty comes from within.


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