Gl-ar750s Downgrade snapshot > stable 'not supported'

I have owned a GL-ar750s router for 2 years now. I upgraded it to NAND and kept it in development thinking any day i will get a stable release I can use. It has been 2 years now and the development snapshots keep getting worse and worse in my opinion and I have a need to downgrade back to NOR if i cant get reliability so i can use a stable release.

How do i downgrade back to NOR from NAND without permanently bricking my device?

back to stock will be acceptable to me. Development snapshot is no longer an option for me.

For what is advertised as "OpenWrt Pre-installed" we should have some good things going on for it but here i am

afaik, openwrt does not endorse pre-installation... you are referring to a half truth from the manufacturer, which is based on an openwrt fork...

if i'm not mistaken, the 'real' openwrt support status and consequently the related support avenues has been greatly diminished by kernel size constraints... which are also primarily the fault / design of the manufacturer...

please update the wiki with contemporary information if you find that what it 'says on the box'... is not what is do-able...

linkage please

commit ae2d249056bdd7b87169e7c14f54c0c464b1acc5
Date:   Wed May 20 12:11:12 2020 +0200

    ath79: nand: disable images for glinet_gl-ar750s
    Fixes following build failures:
     WARNING: Image file glinet_gl-ar750s-nor-kernel.bin is too big
     WARNING: Image file glinet_gl-ar750s-nor-nand-kernel.bin is too big

commit e96bfaedf3a342750d92fbfa773017e40e34bec3

    ath79: GL-AR750S (NOR/NAND): limit factory.img kernel size to 2 MB
    The present U-Boot for GL-AR750S has a limit of 2 MB for kernel size.
    While sysupgrade can manage kernels up to the present limit of 4 MB,
    directly flashing a factory.img with a kernel size greater than 2 MB
    through U-Boot will result in an unbootable device.
    This commit uses the newly-introduced check-kernel-size build
    operation to prevent the output of factory.img when the kernel
    exceeds 2 MB in size, yet permits output of sysupgrade.img
    as long as the kernel is within KERNEL_SIZE := 4096k

commit f0b76d02e8345022d417f02733504cfd862a2d6f

    build: define check-kernel-size to remove unflashable images
    Certain boards have limitations on U-Boot that prevent flashing

commit b97247c2e9cd528206dbe5c55055bd913230eba4

    ath79: gl-ar750s: reduce kernel size to 2M in image Makefile
    u-boot splits nand factory firmware at 2M offset, flash the first
    part as kernel into spi nor and the other part as ubi into nand
    flash. With previous commit increasing kernel size to 4M, generated
    factory firmware is broken because ubi is at 4M offset.
    This commit reduces kernel size definition to 2M in image Makefile,
    producing proper factory image. Partition size in dts is kept
    unchanged so that sysupgrade to a firmware with 2M+ kernel still

Mine is "Dual Flash 16MB Nor + 128MB Nand Flash" so i can easily convert back to the 16MB, I just thought NAND was superior so i did the upgrade.

total flash size is not so relevant in this context...

it is the way that the size is separated... and how the bootloader then 'talks' to those 'areas' that has made support of this device 'complicated/intermittent/less documented'

I'm getting architecture not supported errors on things i never got before. Im at ath79 now but i want to go back to ar71xx stable when everything was working.

well, the two most relevant things you need to follow here are;

  • are you running a stable build?
  • what does the wiki say?

no, I want to run a stable build. This is my end goal.

the wiki has mixed info and i have followed all leads.

yes... wiki portion below;

WIP: Sat Dec 8 12:55:16 2018 version of gl-ar750s-squashfs-sysupgrade.bin results in the message

The uploaded image file does not contain a supported format. Make sure that you choose the generic image format for your platform.
See further

It is NAND firmware for AR750S by default. If you build from OpenWRT official repo, it might be NOR firmware, so you should upgrade it on u-boot web. Please refer to this tutorial

If you want to build a nand firmware, you have to use our repo. 3
Note: As of OpenWrt 19.07.4, gl-ar750s-squashfs-sysupgrade.bin still gives an unsupported format error on the web UI and sysupgrade command, but works fine through the router's debricking interface: power down, ensure only 1 network cable is plugged in, hold the reset button, power on, wait until the led blinks 5 times and stays on, then release reset button. Change your IP to and connect to, where you can upload and flash the sysupgrade.bin image.

OEM installation using the TFTP method
→ generic.flashing.tftp

Certain version produced in 2018 and prior have a bug in the U-Boot implementation that requires Windows for use with U-Boot.

The router works properly once booted; the restriction is only for use of U-Boot over Ethernet.

Only after updating U-Boot can U-Boot be used with macOS, Linux, FreeBSD, or the like.

See the GL-iNet forums for further details and upgrade procedure on a Windows machine.

Upgrade takes just a few minutes, but requires a Windows machine,

Specific values needed for tftp

it is quite unusual for wiki notes ( at least primary install notes for openwrt ) to point to third party repos... and they discuss uboot version updates / complexities here too...

i asked what you are running... ( and it seems we may need to determine what uboot you have also... but as I don't have the device... and the wiki is not clear... I can't really offer much more in assistance... hopefully someone who has force downgraded back to NOR or knows more about determining these versions can take it from here )...

On the plus side... apparently the vendor support (user guidance) is very good... so the vendor forums may offer you a clearer pathway...

oh whoops, OpenWrt SNAPSHOT, r14985-4d4ef1058c ATH-79 NAND build

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ok, very current snapshot... that's no man's land on the wiki... good luck!

Here I am. I'm going to look at gl forum like you recommend however. Thanks.

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also give it a few days if the way forward is not clear... i'm not the best person to be offering advice on this... not worth taking a risk without giving (many) people a chance to respond...

no worries. I will remain diligent. This was my travel router in 2019 and it was awesome; I broke the config in 2020 however. itll get fixed.

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You probably need to help from people knowing specifically that device, like @blocktrron or @jeff

Use stable release ar7xxx generic + block-mount kmod-fs-f2fs f2fsck mkf2fs finally extroot 5 flash