One thread to rule them all: GL AR750S (Ext) Slate - Firmware Update Problems

Hey there, I’ve just had a heck of a time trying to debrick a GL-AR750S-Ext (Slate) router, and thought I would collect my observations in one place because I had to search through like 15 threads on this forum to figure it out.

I do finally have a working Slate with the latest 3.212 firmware, but I had to try, try again, give up, and try again some more before arriving there.

If you are experiencing the following problems updating Slate firmware:

  • In UBoot update, update hangs with “UPDATE IN PR” displayed in the browser
  • In UBoot update, you get “UPDATE FAILED”
  • In UBoot update, update appears to proceed, but firmware does not appear to be flashed and device never restarts
  • In Local Update from GL firmware, you get verification failed

Here are the steps that worked for me

Note: if you plug the Slate into a network using 192.168.8.x (which can happen if your existing LAN also uses a GL-inet router), you will need to change Slate’s “LAN IP.” The Slate’s firmware will warn you about this if you click the Internet tab. I recommend setting this value to if you have this issue.

  1. In U-Boot, flash the 3.104 firmware (.img file)
  2. If flash is successful, log into the router / set up admin password etc
  3. In GL-inet firmware “Local Upgrade”, flash the 3.105 firmware (.tar file), and turn off “Keep Settings”
  4. If flash is successful, log into the router / set up admin password etc
  5. In GL-inet firmware “Online Upgrade”, flash the latest firmware available, and turn off “Keep Settings”

This strange & unusual upgrade path is due to a combination of limitations in the GL-AR750S, UBoot bugs, and so forth.


If you need to use UART to flash

I haven’t had to do this, so I haven’t yet documented the procedure, but please feel free to post here and if possible I’ll add the info to this post/thread.


Maybe your uboot is old.

Have you tried upgrade uboot itself. In uboot failsafe, access and flash this one

Then uboot failsafe mode should work for latest firmware

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It seems there might be some confusion on the weird update procedure I suggest in the original post.

The procedure, summarized briefly:

  1. Flash 3.104 .img file with U-Boot
  2. Flash 3.105 .tar file with GL-inet firmware “local upgrade” interface with “keep settings” turned off
  3. Flash your desired firmware .tar file with GL-inet firmware “local upgrade” interface with “keep settings” turned off

There are specific reasons for doing it this way:

Bugs in U-Boot on some Slates cause problems with properly flashing firmwares newer than 3.104. (This is why @alzhao mentions updating U-Boot in this thread)

Bugs in 3.104 can cause problems with updating to new firmwares from the web interface, so an update to 3.105 is further required before you can reliably flash your target firmware.

I don’t remember the exact details because I forgot them soon after documenting all this, but the documentation is the result of many hours of work. If you are having major problems updating firmware on Slate I would suggest you try following the procedure I’ve worked out and see if it can save you some headaches.