Unable to debrick ar750s

Technical Support for Routers
1

Hi -
Can you possibly advise if it is possible to recover the following:

Problem Summary:

Following failed install of 3.025 device will not reach UBoot

Symptoms

Laptop configured with static IP on ethernet port as 192.168.1.2/24

Unplug device
Insert ethernet cable to laptop
Hold reset button
Power on device
1st LED (power) is lit
3rd (5G) LED flashes 5x and remains off
2nd (2G) LED stays lit

Unable to reach device at 192.168.1.1

Troubleshooting steps:

Following the instructions at Debrick via Uboot - GL.iNet Docs
I am unable to reach the uboot loader to reinstall firmware

Unable to resolve ARP request for 192.168.1.1

2

How old is your ar750s? There was a problem with the U-Boot on the first production batch (up until about December last year) where U-Boot would not respond to anything but a windows laptop. If your AR750s is around that time frame and you are not using Windows to recover, trying doing it from a windows machine.

Otherwise not sure.

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3

Thanks for the advice. Unfortunately, the device is only a couple of months old and the laptop is running MacOS.

Are there any other indications that the system has booted into the uBoot option correctly (e.g. both LEDs - for power and 2G remain solidly lit after releasing the reset button after 5 flashes).

4

My first AR750S was delivered by Amazon US in December, 2018. It had the older U-Boot and I needed to update. That would be the first thing that I would try. A Windows machine is required. It took me under 15 minutes, from walking up to a friend’s Windows machine to confirming success.

5

Thanks Jeffsf - will try to find a windows box as you mention.

6

One additional point, I note that from a packet capture it is sending traffic on a 802.1q trunk on VLAN 1.

Adding a VLAN sub-interface to the ethernet interface on my Mac does allow it to respond to the ARP requests for 192.168.1.2 that I can see coming from the ar750s, however nothing much happens after that.

7

Those are the symptoms I was experiencing.

From the previously linked thread

You can check the uboot version after the device boot up.

root@GL-AR750S:~# strings /dev/mtd0 | grep -nr "U-Boot" | head -n 1
348:U-Boot 1.1.4-gcf378d80-dirty (Aug 16 2018 - 07:51:15)
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8

Just a quick note to say thank you.

Managed to get in front of a windows machine today and recovered the device within a few minutes.

Never seen that before, but guess you live and learn.

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