RT-AC66U A1 and non-working 5 GHz

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Senior Member
Hi all.

I am running Merlin 380.70_0 on RT-AC66U A1.
From some time 5 GHz module stopped working: the control band is 0, the temperature is "disabled" but all settings are active. Corresponding LED is on.
Yesterday I have performed "mtd-erase -d nvram" command for some specific reason and it looks like 5 GHz WiFi was observed, but when I restored settings - it becomes non-working again.
I am not sure is it software or hardware problem and I don't want to spend ages for putting all settings back after factory reset just to see it is hardware-based.
So my questions are:
  1. Is there any way to test operability of WiFi radio inside the router?
  2. Is there any specific nvram settings those could affect this problem?
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Very Senior Member
You were on the right track until you restored settings. Do a hard factory reset and configure manually. Do not restore old settings! Might just work or it might be time for new hardware.


Part of the Furniture
First, if you're running this on an external, internet-facing router, I would not be running that old firmware on the router today.

Either flash the latest from Asus or (recommended) the @john9527 RMerlin fork instead.

You'll probably need Rescue mode to get the firmware updated.

And afterward, you will need to reset it to properly test for hardware issues (or not).

Fully Reset Router and Network

As @bbunge states, do not restore old settings. You effectively undid everything you 'reset'.

BTW, I would also not use those commands on the router myself. The Reset button, WPS button, and the GUI reset to factory default methods are much safer and effective too.


Senior Member
Nah, this router is almost 10 years old. I'd rather buy newer model than restore all settings one by one with no warranty the result will be OK.
I thought someone can recommend some sensitive nvram setting to play with. If not - thanks a lot, but it's not what I need.


Part of the Furniture
Then before doing the steps suggested above, make a backup config file (from the GUI) and also download the firmware that the router is on today. Put these in a safe place and use them to get back to your current settings in the shortest time possible (only a few minutes).

Then, do the suggestions above.

You may save yourself a bucket of cash and get a more secure network too. :)

BTW, the router is at most around 8 1/2 years old today. There's still life in it! :)


Senior Member
Guys, please pay attention on what I have posted.
Then pay attention on my questions.
Read the info. There is no newer Merlin firmware for my router.

Please stop posting something I didn't ask. New RT-AC66U B costs about $120 in my country. Bucket of cash? Really? I think you'd better find a better job in this case.

Once again: if you don't know the answer on my questions - it will be better to be quiet. It would be wiser at least.
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Part of the Furniture
Please pay attention to what we responded with.

If you have questions, ask. But not considering the suggestions made at all makes me wonder why you're asking for help in the first place if you don't want to take it?

We need to start at a good/known state to troubleshoot anything, in any coherent way.

If your budget allows for a new router, buy it.


Part of the Furniture
@bbunge, that link was provided above.

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