[Solved] WRT1900ACS spontaneously reverts to stock firmware

I have recently installed OpenWRT on a new WRT1900ACS router and have done some preliminary configuration through LuCi as I learn a bit more about it. Today I was not able to log in either via HTTPS or SSH. I eventually discovered that the OpenWRT firmware had been erased and it was back to stock Linksys firmware. Is this normal and what might have caused it? It's a bit unsettling as I've only been using OpenWRT for a few days.
Any advice would be appreciated. /Ross

I don't think it has been erased. Your device has a fallback partition (which still has the stock firmware by default). Maybe you got a power outage or some other 'irregularity' which made the device boot to your fallback partition. OpenWrt is probably still there. See the wiki page for the flash layout. I have no idea myself though how to trigger your device to boot from the primary partition again.

See this OpenWrt how-to post...


Your router rebooted at some point, had an issue booting from the partition with OpenWrt on it, and after unsuccessfully booting it, auto switched to the alternate partition.

The recovery procedure is in the WRT AC Series' ToH page, however since the migration of the ToH page changed how headings are recognized, until I or someone else fixes the sub-headings, it can't be directly linked to.

It's in the TOH. The new link...


The OpenWrt post goes in to more detail.

Hi all,

Thanks so much for your prompt and detailed responses. Yes, that was the problem and I now have OpenWRT running again :slight_smile:

There is one aspect of this that is bothering me though. From what I understand, the router would have started with image 1 (Linksys) and is now running image 2 (OpenWRT), confirmed using '/usr/sbin/fw_printenv -n boot_part'. As I understand it, the configuration files of each image are held in their respective flash partitions using overlay fs. However, when the router switched back to the Linksys firmware, the IP address had changed to 10.x.x.x whereas it was 192.168.1.x when I originally programmed OpenWRT before switching over. So why has the IP address changed? What am I missing here?

Cheers, Ross

It would have had to have been manually set to the 10.x.x.x/24 subnet at some point, as Linksys does not use that subnet for the WRT AC Series (if any of their devices)... all WRT AC Series devices come with a subnet by default from the factory.

I've only had the router for two weeks so I remember exactly what has happened to it. I purchased it specifically for the purpose of installing OpenWRT. So all I did when I booted it up was to change its IP address to (as I subsequently connected its WAN port to my existing LAN which is at After confirming that I had internet connectivity and that the router was basically working, I proceeded to the firmware update page (now at and installed OpenWRT. After the reboot I was in OpenWRT until it spontaneously switched back (for some unknown reason a week or so later). From then on the router was at Perhaps the cause will have to remain a mystery!

It would have had to have been manually changed by someone with physical access to the device in the past two weeks, as flashing occurs via a round-robin...

  • When you flash outside of Uboot, whatever partition you're flashing is the one you're not currently booted to.
    • The only way the IP could have changed from the subnet is if someone who had physical access to it in the last 2 weeks changed it.

  • The only manufacturer I'm aware of that utilizes the 10.x.x.x subnet blocks on their routers, by default, is Apple

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