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Asus AC86U: broken 5GHz band!?

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Occasional Visitor

I am reaching out to you guys, hoping to get some feedback on what could be wrong with my Asus AC86U.

I have used the router for months without problems in SmartConnect mode and have assigned my client devices to either the 2.4GHz or 5GHz band by using the wireless MAC filter functionality. Everything has worked very well until Thursday. I left my apartment early in the morning, got back home in the evening and nothing worked anymore.

Of course I did the normal troubleshooting (power off/on, reset, even back to factory settings, 30/30/30 etc..) but nothing has helped.

I did some investigation over the last two days and I have noticed that the 5GHz band seems to be the culprit here. I have noticed that my client devices which are connected to the 5GHz band keep connection, however, there is no more data traffic throughput (see access list below). Client devices connected to 2.4GHz keep working perfectly fine. The iPad has no access time, when opening the iPads browser there's no throughput. I also noticed that the access timer stops while the 2.4GHz connected devices keep counting.

Bildschirmfoto 2019-07-27 um 10.40.10.png

Then, the channel list shows me that 5GHz band always changes to 0:

Bildschirmfoto 2019-07-27 um 10.43.08.png

At the same time, the 5GHz band settings no longer show all available channels; instead, the drop-down field only contains the "auto" value instead of all the normal channels:

Bildschirmfoto 2019-07-27 um 11.04.38.png

Lastly, I noticed the following code in the system log (which does not tell me anything to be honest as I am not network specialist). See attachment "syslog"

I am just hoping that these findings here may indicate what could be wrong with my device. I also changed back to the earlier AsusMerlin firmware 384.11 and even flashed back to the stock firmware but the problem remains.
Any feedback is appreciated :)


  • syslog.txt
    15.9 KB · Views: 267
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I´m facing the exact same problem.
Sorry I can´t help. Google search brought me here :(

Edit: Choosing "auto select channel" in 2.4Ghz, resulted in the 5Ghz band changing also and the 5Ghz re-appeared on my computers network list.
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No worries. The strange thing though is that the 5GHz band works for 1-2 minutes following a router restart but then the problems reoccur.
Thanks, but that didn’t work for me. The 2.4GHz channel was set to „auto“ already, after changing it to a particular band and back to auto made no difference.

Even disabling the 5GHz band in „Wireless —> Professional“ settings and re-enabling it does not bring it back to life. Only a restart helps but then it disables again shortly after.
I had the same problem with a client's router (also RT-AC86U). It was a hardware problem, and I've heard of others also having failed 5GHz channels on these units. ASUS made good on mine under warranty, but it was a protracted and painful process. (If my time was being billed for it just buying another router would have been far cheaper. And to add insult to injury I had to pay return shipping.)

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