WRT1900ACS V2 reverted to stock OS after power flicker

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austin457
DD-WRT Novice


Joined: 08 Nov 2020
Posts: 4

PostPosted: Sun Nov 08, 2020 16:57    Post subject: WRT1900ACS V2 reverted to stock OS after power flicker Reply with quote
WRT 1900ACS V2 was flashed with DD-WRT (years ago).
Had power outage, when router rebooted it was running the factory OS. (Yes, my bad. I have since bought a UPS).
I've read these have 2 partitions and most likely the DD-WRT image is still on it, but there is no option on this thing in the factory OS to enable SSH. So I don't know how to flip it back to DD-WRT.
The factory OS is so bad I installed DD-WRT the first week I had it, and have not touched it since. So although I don't remember what DD-WRT version I was using it's safe to say it's way out-of-date.

My Question is 2 part:
1. How/should I just have it revert back to the DD-WRT it was running. Not asking how to re-flash, asking if it is possible to restore without flashing.

2. Recommendations for the best stable DD-WRT build to use if I do re-flash, since it is probably a good time to update.

I'm currently going through the forum to try to find my answer for #2, but I'm getting lost in TMI. I'm not a tweaker, I just want the best stable build. It's been so long since I did this I'm having to lookup the basics on how I even did this the first time.
I do need both 2.4 and 5 GHz wi-fi and use Windows' file sharing on my LAN. I mention this because so far the latest build stuff I'm seeing mentions issues with SAMBA.

Thanks to the community for such a great product.
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blkt
DD-WRT Guru


Joined: 20 Jan 2019
Posts: 2030

PostPosted: Sun Nov 08, 2020 17:35    Post subject: Reply with quote
From Linksys GUI locate Troubleshooting, Diagnostics tab then click "Restore previous firmware" button.

This switches the boot partition then reboots; it should bring you back into DD-WRT.

Before Kernel Samba 12/29/2019 - r41813

Recent Fallback Build 08/02/2020 - r44048

Current as of Writing 11/03/2020 - r44715

Whether KSMBD/CIFSD will work for you depends configuration, operating systems, file systems etc.


Last edited by blkt on Sun Nov 08, 2020 17:55; edited 1 time in total
austin457
DD-WRT Novice


Joined: 08 Nov 2020
Posts: 4

PostPosted: Sun Nov 08, 2020 17:52    Post subject: Reply with quote
Thanks for the fast reply.
I just tried that and it just went back to the stock OS. So I guess that answers question 1.
Looks like I'll need to re-install DD-WRT from scratch.


Last edited by austin457 on Tue Nov 10, 2020 16:58; edited 1 time in total
austin457
DD-WRT Novice


Joined: 08 Nov 2020
Posts: 4

PostPosted: Sun Nov 08, 2020 20:03    Post subject: Reply with quote
I just attempted a flash using factory-to-ddwrt.bin r44715 from:
https://download1.dd-wrt.com/dd-wrtv2/downloads/betas/2020/11-03-2020-r44715/linksys-wrt1900acsv2/

It rebooted back to stock OS.
I had read that doing a hard reset was no longer recommended for these units. So at this point it has only performed a soft reboot. I would normally just perform a reset button action and see what happens but since I'm already on the forum I figured it would be good to ask about it first.

Again, thank you and the community for helping people like me.


Last edited by austin457 on Tue Nov 10, 2020 16:55; edited 1 time in total
blkt
DD-WRT Guru


Joined: 20 Jan 2019
Posts: 2030

PostPosted: Sun Nov 08, 2020 21:49    Post subject: Reply with quote
Where did you read that? May have confused hard reset with 30/30/30 which is only for really old hardware such as WRT54GL.

I always hard reset after entering a new firmware environment (stock to dd-wrt and vice versa). Also, consider a hard reset after a successful upgrade when the jump between build numbers is large.

If holding the reset button for 10 seconds is out of the question, sure can use "Restore Factory Defaults" from DD-WRT's web interface under Administration -> Factory Defaults.

There are ways to reset from Telnet/SSH, most recently is "nvram erase && reboot" after login as root.

Also there is nvram clear; after digging around in DD-WRT code I suspect this is what GUI "Restore Factory Defaults" uses.

When upgrading from DD-WRT web interface via Administration -> Firmware Upgrade, there is a dropdown option labeled "After flashing, reset to" and I highly recommend to always keep this selected "Don't reset" to avoid problems.

Again digging around code this dropdown option appears to use erase nvram, which is not to be confused with nvram erase, and has been known to cause problems in the past for some Linksys routers.

WRT1200/1900 series has a Linksys GUI firmware upgrade limitation, the file size cannot be much larger than 32MB.

So, because of this it's necessary to go back and grab a build from the first half of 2018 to use for factory-to-ddwrt. Then upgrade again using DD-WRT's GUI and webflash.bin to your target build.

BTW you don't have to quote me every time; there is post reply in the lower left (also see quick links in the upper right).
austin457
DD-WRT Novice


Joined: 08 Nov 2020
Posts: 4

PostPosted: Mon Nov 09, 2020 0:00    Post subject: Resolved Reply with quote
Thank you for correcting my mis-understanding in regards to resetting (button).
The issue with the image not taking was the file size. I had seen mention of this size limitation, but failed to pay attention to the file size I was attempting to use.

As you instructed, I first used a file from 2018 that was less than 32, after successfully booting in DD-WRT after a reset I then installed r44715 and all is well. I can relax again. That stock UI had me stressed out.

Now to get my LAN mapped back out nicely, and check out the new firmware. I've been using something a few years old. Very Happy
SurprisedItWorks
DD-WRT Guru


Joined: 04 Aug 2018
Posts: 1055
Location: Appalachian mountains, USA

PostPosted: Mon Nov 09, 2020 22:15    Post subject: Reply with quote
I kept careful notes on the size issues for this router, and if you stay away from build 06-30-2019-r40167 through build 08-31-2019-r40863, you'll be fine in either partition.
_________________
Five WRT1900ACSv2's on 42926, 44048.
VLANs, VAPs, NAS, client-mode travel router, OpenVPN client (AirVPN), DDNS, wireguard servers, wireguard clients (AzireVPN), two DNSCrypt DNS providers (incl Quad9) via OpenVPN/wireguard clients.
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