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 2.0.2.188405, 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 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. 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 192.168.1.1 (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.

By Vegard Vines Skjefstad

15 replies on “How To Install OpenWrt on a Linksys WRT1900ACS”

Great info thanks – I’ve been using my Linksys EA8500 for 2 yrs now with the stock eom firmware. Now I want to switch to OpenWRT and take greater control of the firewall.

Should I reset the router to factory defaults before I start following your instructions above?

First of all, note that the instructions above is for another router than yours. But if OpenWrt supports your router, the instructions should work on that, too.

It shouldn’t matter if you reset your router to factory defaults before you start the process of installing OpenWrt or not, but I’d do it anyway so you’re starting the process with a clean sheet.

I’ve followed your steps with the latest firmware on a WRT1900ACS (openwrt-18.06.4-mvebu-cortexa9-linksys-wrt1900acs-squashfs-factory.img)
It seems to work fine, up to the reboot. On the reboot the router boots into the stock firmware rather than openWRT. Not sure if this is an auto revert due to an error or a failure to load thefirmware in the first place
any suggestions would be welcome

Not sure what to make of this. Do you have more routers on your network? It might be that you accidentally flashed another router with the OpenWrt firmware. If not, I’d just try to flash the router with OpenWrt again. If that doesn’t work, there are several things you can try:

  1. Try to flash with an earlier version of OpenWrt, then upgrade to the most recent version once OpenWrt has been successfully installed on your router.
  2. If that doesn’t work, try to flash the router with the exact version of the Linksys firmware (version 2.0.2.188405) that was on my router when I installed OpenWrt, and then try to flash OpenWrt on top of that version.

thanks. I do have other routers in my network, but they’re allready running openwrt.
my routers firmware is at 2.0.2.188405 at the moment.

Where do I find an earlier version of OpenWRT?

found the issue thanks to your comments.

turns out the currently installed firmware 2.0.2.188405 is incompatible with this router as it is v1 hardware. It needs 1.0.3.187766

after flashing that to the router with the original firmware I was able to update to Openwrt using the process above.

thank you for your help

Good to hear to figured it out. And thanks a lot for posting the solution, it can help other people in the future.

Hi, i’m using openwrt on a wrt1900acs and i’m having a lot of issues with wifi that randomly blocks (sometimes cannot even ping the gateway, but clients see themselves associated) or drops speed to 1Mb or less.
While this happens, cabled clients are not affected and turning off/on wifi does not solve the issue and a device reboot is required.
Seems not to be related with traffic load or channel congestion (it may happen also with just 1 client).
Some web searches point out that’s a driver issue, ’cause marvell is no more mantaining it and known problems will never be fixed.
These blocks render my connection unreliable, and i’m thinking to buy another device that is really fully supported (just for me it seems like a scam to advertise as “open source ready” a device that is partially bugged with issues on github opened more than 2 years ago?)
Do you have suggestions about it or feedbacks for real world scenario? (I mean long-term daily usage of the network, not just testing a configuration)

I don’t have any suggestions for this particular issue. But I’ve had some problems with WiFi stability in the latest versions of OpenWrt, and at one point I had to downgrade to version 18.06.1.

I’ve also seen some suggestions that says you should use Davidc502’s build of OpenWrt on the WRT1900 ACS, but I haven’t done that myself. If you feel adventurous, the build is available over at https://dc502wrt.org/.

If you go down that road, please let me know how everything turned out.

Q: Is it correct that when you try to open the latest firmware of open WRT it give you an error messagethat says: “The image disc is corrupted”, thanks!!

No, that’s not correct. Perhaps downloading the firmware again help. And make sure you download the right version. If you’re flashing for the first time, download from the “Install URL”. If you’re upgrading an existing OpenWrt install, download from the “Upgrade URL”.

Thanks for the quick reply, I am doing for the first time on my Linksys WRT 1900ACS and of course I do not want to broke the router!!

Already tried latest dc502 build: it seems a little more stable and comes with some useful software preinstalled, but i still had wifi issues.
Yesterday i flashed lede 17.01.7 and will see, now my roommates are away for holidays so i have to wait some days before having a complete feedback.
I’ve just another question: yours is a v1 or v2?
Mine is a v2, from what i understood the only difference is v2 has some fcc rules hardcoded into chip’s firmware; maybe this is the cause of driver’s instability?

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