RT-AC66U B1 woes (can't update firmware)

[osmanaut]

Hey everyone,

So I recently bought an AC66U and really want to install Merlin, but for the life of me I can't get it to work and I don't know why.

Here's what I've tried:
- Using the GUI to upload the Merlin RT-AC68U_360.68_4 firmware, that gave me a "Firmware upgrade unsuccessful" error which I believe is something to do with FCC restrictions seeing as I'm using firmware 3.0.0.4.380_3264

- I read that you can get around that using the firmware restoration tool Asus provided - but that didn't work either.

- Put the router in to recovery mode as you would with the restoration tool, then used the MiniCFE web server to upload the firmware. Everything looked fine then, the file uploaded, router reset itself, but then I logged in and it was still running the old firmware.

I've reset the NVRAM before and after attempting to flash, but nothing seems to work.

I'm running out of ideas and not sure how to proceed. Has anyone else come across this?

Thanks in advance

 

[Jack Yaz]

Hey everyone,

So I recently bought an AC66U and really want to install Merlin, but for the life of me I can't get it to work and I don't know why.

Here's what I've tried:
- Using the GUI to upload the Merlin RT-AC68U_360.68_4 firmware, that gave me a "Firmware upgrade unsuccessful" error which I believe is something to do with FCC restrictions seeing as I'm using firmware 3.0.0.4.380_3264

- I read that you can get around that using the firmware restoration tool Asus provided - but that didn't work either.

- Put the router in to recovery mode as you would with the restoration tool, then used the MiniCFE web server to upload the firmware. Everything looked fine then, the file uploaded, router reset itself, but then I logged in and it was still running the old firmware.

I've reset the NVRAM before and after attempting to flash, but nothing seems to work.

I'm running out of ideas and not sure how to proceed. Has anyone else come across this?

Thanks in advance

You're trying to flash AC68U to an AC66U? Or is there a typo somewhere

EDIT: sorry just saw the B1 which means AC68U is right f/w

 

[osmanaut]

You're trying to flash AC68U to an AC66U? Or is there a typo somewhere

I've got the B1 revision and according to the wiki: "RT-AC66U_B1 (use the RT-AC68U firmware)"

I have since found a couple more threads on the topic, and am now trying to downgrade to a 376_* firmware, followed by upgrading to 378_*, then hopefully Merlin. Let's see if this works!

Edit:
Nope, going from 380 > 376 > 378 works, but from 378 to Merlin fails. Skipping 378 fails too. Using the recovery tool, I get "Failed to upload the firmware file. transfer cancelled". Which is what happened trying to go from 308 to Merlin.

Edit 2:
So I thought I had it all figured out, the router was using CFE 1.0.2.0 which needed a downgrade in order to flash custom firmware. Followed a guide and successfully rolled back to 1.0.1.6 (EU) as confirmed by running `nvram get bl_version`. I cleared the NVRAM and tried flashing to Merlin RT-AC68U_360.68_4 through the GUI - no dice. Then again through the Firmware Restoration tool and nada. Not quite sure where to go from here...

 

[RMerlin]

Try a different browser, and disable any security suite. The RT-AC66U_B1 should directly be flashable with 380.68_4, as it was never available with the old 32MB firmware. No specific CFE or firmware version needed.

Also, make sure you DO have an RT-AC66U_B1, and not an older RT-AC66U HW revision B1. If the stock firmware doesn't show AiProtection, then you have the old RT-AC66U.

 

[osmanaut]

Try a different browser, and disable any security suite. The RT-AC66U_B1 should directly be flashable with 380.68_4, as it was never available with the old 32MB firmware. No specific CFE or firmware version needed.

Also, make sure you DO have an RT-AC66U_B1, and not an older RT-AC66U HW revision B1. If the stock firmware doesn't show AiProtection, then you have the old RT-AC66U.

I can't thank you enough! Turns out I've got the older router - seeing "HW Ver B1" on the box threw me off.

Do you think I should restore the CFE back to 1.0.2.0 or will 1.0.1.6 be ok?

 

[ColinTaylor]

Do you think I should restore the CFE back to 1.0.2.0 or will 1.0.1.6 be ok?

Presumably you flashed your router with the CFE from the wrong model, that doesn't sound good. If I were you I'd definitely want to put back the original CFE. You did make a backup, right?

 

[osmanaut]

Presumably you flashed your router with the CFE from the wrong model, that doesn't sound good. If I were you I'd definitely want to put back the original CFE. You did make a backup, right?

Yep I made a backup. The CFE I used was from this page, specifically `1.0.1.6 (EU)` under `RT-AC66U (MIPS) - (HW Revisions: 1.30, 1.50, 1.60)` which it turns out is for the older AC66U (I think?). So it's most likely the correct model and I double checked the flash chip was a Zentel.

 

[ColinTaylor]

Ah OK. From what you said earlier it sounded like you were using a CFE from a 68U. Either way, personally I'd put the original CFE back just for my own piece of mind (you can always change it again later if you really need to).

 

[osmanaut]

Ah OK. From what you said earlier it sounded like you were using a CFE from a 68U. Either way, personally I'd put the original CFE back just for my own piece of mind (you can always change it again later if you really need to).

Yeah I'll admit I found this all a bit confusing, seeing as it's my first time flashing any kind of hardware! I'll most likely end up restoring the backup tomorrow morning (this has kept me up late).

The guide I followed seemed to imply that the original CFE wouldn't boot up other firmware (I'm guessing Merlin's a special case that isn't blocked) and I might give Advanced Tomato a try.