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Asus RT-AC66U issues connecting to 5 ghz band

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Please try this when having issues seeing the 5ghz network

I also have a lot of issues with my ASUS RT AC66u router.

The 5ghz frequency is not visible / seen by clients or the 5ghz network disappears after some time. The 5ghz is active according to the router setup page and the LED on the router, The only way for me to connect / see the 5ghz network again is by booting the router in recovery mode and then restarting it and boot normally again. I've posted a complaint to ASUS and i urge everyone experiencing this problem to do so too, so that they can fix the firmware.

Detailed problem solving instructiions:

- turn of the router with the power button.
- keep the reset button pressed and turn on the router with the power button.
- as soon as the power led start blinking (very slowly ca. once every few seconds), you can release the reset button, but give the router some time to fully boot in recovery mode.
- once the router is fully booted in recovery mode just power it off by pressing the power button again.
- once turned of just turn it on again by pressing the power button.

After this procedure i can once more see (and connect to) the 5ghz signal again. This procedure has to be repeated every time the 5ghz network is invisible.

Please tell me if this procedure works for you to, so we can collect information on this issue and have it fixed by ASUS.

Keywords:
RT AC66u,
can't connect to 5ghz,
no 5ghz signal,
5ghz issues
5g not visible
5g hidden
ASUS USB AC53
5ghz network not seen
Edit/Delete Message
 
Have the same issue as you. Try your instructions help but signal disappear again. Have you find the solution?
 
Have same 5ghz disappearance issue

I have the same issue, however I am not able to get the 5ghz band to return even with the recover mode trick you described. I will contact support to get an RMA unless they can acknowledge and release a fix for this soon.
 
Having the same issue here... 5G worked for about 20 min, but I cannot see the SSID any longer.

How did you guys manage to solve this?
 
5GHz is not visible for me either

I also have the same problem of an invisible and completely inaccessible 5GHz network (as described by others in the posts above) except that I'm using an RT-AC68U.

I'm new to networking, and I only just got this router a few weeks ago, so I spent considerable time (spread over a period of several days) finding my way around the settings, reading up about them, and then adjusting them to my requirements. During all of that time, the 5GHz network worked fine.

I then decided to upgrade the firmware from 3.0.0.4.374_205 to 3.0.0.4.374.371 (which was the newest stock firmware at the time). After the update, I manually re-entered all of my settings, and again I found 5G to be working fine. However, it wasn't until the following day (when I next needed to connect wirelessly) that I noticed the 5GHz network had just disappeared.

I'm not saying that the two things are definitely related, just that they happened roughly around the same time as each other. But that may just be coincidence.

Since that time, none of my devices have been able to see the 5g network at all.

5GHz shows as active on the router's wireless settings page, and the corresponding LED is lit up on the front of the router too. But yet no 5G SSID is detectable, even though it is being broadcast.

I tried recovery mode (as mentioned above) but it didn't make any difference.

I also tried changing from stock firmware to Merlin's firmware (which I was planning to do anyway) just of the off chance that it might make a difference. But it didn't.

I have no idea what to do next.
 
What are people doing about this problem?

I've already contacted Asus support (who were worse than useless).

They basically just told me to reset the device (even though I had already made it clear to them that I had done a full factory reset and it made no difference).

They've now just told me to speak to the retailer, and they've washed their hands of the situation.

Even if the retailer does agree to an exchange, what's so say it won't just happen again?

Several people in this thread have said they have the same problem, but nobody has said what they've done about it?
 
Channel set to high by default

It appears that the channel is set to high in auto mode (something like 100 or above).
Set to something like 44, 48 will make the SSID visible again.

A new driver for this very fast nic would be nice Asus!
 
AC66 5G Dropouts <One Characterization>

Concur with the above, something is wrong with 5G on channels. I observed total 5G aperiodic drop out repeats on channels:
149
153
157
161

Background:
Finally set up a new-to-me AC66R refurbished router today. It came loaded with factory F/W 3.0.0.4.374.5517

I left that (OEM F/W) loaded for a while just to set things up, play aournd, and check out a few features. A couple of key observations stood out:

1) Off Topic - Transmit Power GUI came set to 80mW. I played around with InSSIDer and WiFi Analyzer to see if any noticeable change would happen above the 80mW setting. I entered 85, 90, 100 and 200 with no noticeable change in received signal power (db) to two 2.4G clients (Samsung G3 or HTC EVO) I had set up at the far corner of my house with my son observing and reporting. I went back down to as low as 1mW just to see if the GUI was just a placebo, and although the received db didn't seem to change much, the clients were warning of lost connections. Seems the GUI does something to a point. I did not test connect/download speeds at the various settings.

2) On Topic - The second and most disturbing observation today was the total periodic loss and recovery of the 5G signal. Observing InSSIDer, you could plainly see the signal appear for a few seconds, then totally drop out for a few seconds then return. Didn't seem to be a set periodicity, but the phenomenon certainly repeated itself over and over again, obviously observable and unmistakable.

I then loaded Merlin Fork 374.43_2-06 with the hope that it was isolated to the OEM firmware, but the phenomenon repeated.

After trying a few resets/factory resets/nvram clear, still no change.

I then decided to try and characterize the issue. Initially I had AC66s 5G channel GUI set to AUTO (which it always assigned - 149 as observed on inSSIDer, and saw the issue)

I then asked by son to manually select each of the 5G channels manually one at a time to we could observe any trend or pattern and characterize.

Here is what we observed on manual assignment:
Channel - Observation
36 - Appears Stable
40 - Appears Stable
44 - Appears Stable
48 - Appears Stable
149 - aperiodic Drop/shutoff and repeat
153 - aperiodic Drop/shutoff and repeat
157 - aperiodic Drop/shutoff and repeat
161 - aperiodic Drop/shutoff and repeat
165 - Appears Stable (as a 'higher channel', I expected the drop/shutoff phenom, but did not observe it)

I hope this helps someone, until it can be root caused and corrected. I did not try any of the latest 376 series firmware to see how those perform, but anyone experiencing the issue might try manually setting the 5G channel to one of the ones appearing stable above, and not manually selecting or allowing channel AUTO selection to assign any of the suspect ones.

Maybe ASUS or Merlin can surf the code and see what the root cause might be, and save others some further heartache....

I suspect the vast public leave their channel selection in AUTO,and if it assigns one of the suspect channels, they are probably cursing everything in between and including the router.


Expanding Keywords from poster above:
RT-AC66u,
can't connect to 5ghz,
no 5ghz signal,
5ghz issues
5g not visible
5g hidden
5ghz network not seen
5G Drop
5G periodic drop
5G dropping connection
5G can't connect
disappearing 5G
5G stability
5G instability
 
If you can, please try...
For Merlin FW, on the Wireless/Professional tab for 5GHz, try setting the Regulation Mode to 802.11d or 802.11d+h (try each one). It appears that some of the newer client wireless drivers depend on this info being sent.
 
Last edited:
John,

Thanks fro the reply. It just does not look like a client side issue, since only some channels are affected.

Since only specific channels, I wouldn't expect global settings to show any difference.

That said - I did get a chance to try them today d, h, d_h, with no change.

Did a short video to capture samples of the phenomena, along with the above checks you asked for.

(Click on pic or link to view)



http://vid154.photobucket.com/albums/s257/kenhdog/General/AC66_5G_Channel_drop_zpsh1wiibex.mp4

Driver issue? Firmware issue?

Broadcom? Asus?

Must affect lots of folks to some degree; I see 68,000 views on this thread, probably some related....

Interesting only certain channels; that should tell someone something...
 
@kenhlan

Where are you located....US or EU? And did you purchase the router in the same region?
 
US coded (as verified in nvram) and US purchased.

The log in the GUI doesn't show anything when the shutoff occurs. Is there a log somewhere else which might capture the state change or anything?
 
Last edited:
Do you have another device (non-Android) to test with? In my searches I found the following.....

http://www.androidpolice.com/2014/0...uble-connecting-to-5-ghz-wi-fi-access-points/

I'm out of any other ideas here. I know there are many people running the router without problems. You may want to consider exchanging the router just to rule out a hardware problem (it may have been sent back originally to be refurb'ed for a reason).
 
Thanks.

Tried on my kids iPad, same results with one of the suspect channels (153).

As expected 153 under test was unable to connect and appeared then disappeared from the survey list, over again. Changed to 44 and all was well.

Router seems to work fine on these channels
36 - Appears Stable
40 - Appears Stable
44 - Appears Stable
48 - Appears Stable
165 - Appears Stable

These channels are unable to connect and appear then disappear from the survey list, repeatedly
149 - aperiodic Drop/shutoff and repeat
153 - aperiodic Drop/shutoff and repeat
157 - aperiodic Drop/shutoff and repeat
161 - aperiodic Drop/shutoff and repeat

If you happen to be or set to a stable channel, you'd never know.

Tried a few different flavors of Firmware, OEM 376 series, Merlin 376 series, Merlin 374 series, and then back to Merlin Fork 374-43_02.06 all wiht no change and nvram clears between.

Would be interesting to start a survey/inquiry thread to see others test results on those specific channels...
 
Last edited:
I have two AC66U's, one running as a router, running Merlin 3.0.0.4.374.38_2; and the other one, running as a repeater (on a different floor), running Merlin 374.41. I have tried various firmware as well, including the official 372's, 374's and various 376's, as well as Merlin up through 376.48

I am located in the U.S., and presume that both of my AC66's are coded for U.S. channels. I've not done anything to change the bootloader (except to the extent it is changed when flashing FW)

I have the router currently set up as follows:

2.4ghz band-- channel 1--20/40mhz mode

5.0ghz band-- channel 161 (extension "auto"), 80mhz mode

The repeater is set to repeat the 5.0ghz band, and so it too is set (automatically in repeater mode) to channel 161. It rebroadcasts 161 on the 5.0ghz band, and it is set to channel 6 for the 2.4 ghz band.

Both devices have different SSID's for each of the two wireless bands.

I have tried all of the channels available in both the upper and lower portions of the 5.0ghz spectrum (e.g., 36, 40, 44, 48, 149, 153, 157 and 161) and I have never had any issues with devices not being able to connect, or dropping off, or any instability with the 5.0 ghz band. Never a dropped signal, and I can "see" and use the 5.0ghz band with all of my dual band ASUS AC1200 USB clients, and with my single band ASUS AC600 USB clients, as well as with a WD MyBridge AC single-band bridge. All channels are also stable with my Samsung Galaxy S5's AC, as well as my wife's (she has the same phone).

Parenthetically, I also flashed the dreaded 3602 official firmware before I'd read the threads here. I didn't see any interruption of the 5.0ghz band, at least none I'd noticed. I did not care for the FW (since it seemed to give me less range than the Merlin 374.xxx I had been using before flashing, so I did a factory reset and then reflashed with the FW I am currently using, all with no ill effects.

Off topic: BTW, I will tell you how stable and solid my 5.0ghz is: I just purchased a Dell Chromebox (terrific deal, $169) which has an AC wireless NIC built-in (it's an Intel AC 7260 wireless card) and I have to say this Chromebox is not only the single most stable device I've ever had and the easiest to set up (literally plug it in and go), but it is also the single fastest wireless device I've EVER used...ever. Yes, this is now officially off-topic, but I'm pretty much in awe of this Chromebox device: I ran several speed tests (I like the AT&T speed test best, because it has the lowest overhead and no junk ads like Speedtest.net has...they both use the Ookla engine, but AT&T's site is much cleaner). I was absolutely floored by the results: The Chromebox is situated two rooms away from the router (on the same floor/horizontal plane), and connected wirelessly to the 5ghz band (channel 161). Despite it being a wireless connection (and I do not know the connection throughput speed because I don't know how to query the adapter in the Chrome OS), it was as though the thing had a Gigabit Ethernet connection. I repeatedly was seeing 323Mbps+ download speeds, which is exactly the speed I see from my wired computer that is connected directly via Cat6 cabling to the my AC66U router. I have TimeWarner's "Ultimate" package, which is sold as "300/20", but with a wired GigE computer, I routinely get 323+ download. To see this on a wireless device was just amazing. At least to me it was. Chrome OS has to be the thinnest, lowest overhead thing around.

Back on topic: Anyway, I've not experienced any of the issues you folks are having. My AC66U's are rock-solid and able to connect to anything I have thrown at them, and that's more than 20+ clients (all either 802.11n or 802.11ac). I have used various wifi analytics tools (Inssider, WiFiAnalyzer for Android, and others) and have not seen any fluctuations in signal strength in either the 5ghz (or 2.4ghz) bands, regardless of the channels I use.

I suspect you either have a bad unit (as John mentioned, it was likely refurb'd for a reason), or you have some peculiar environmental issues that are messing with the upper-end channels on the 5ghz band, and I have no idea what those could be.
 
Last edited:
Thanks jeg for taking the time to reply.

Certainly add some perspective and a couple of other things to try just to see.

Anyone else have expeience similar to mine on those channels they could try?

Really appreciate in helping me characterize this issue.
 
kenhlan:

One other suggestion. I just came across an interesting tool called Vistumbler which is available at http://www.vistumbler.net/. Download it (assuming you're running Windows) and run it but with your wifi adapter disconnected from your router/AP. It functions a lot like Inssider and other tools, but it has some very nice real-time graphing features which let you see the transmission rates/power for any particular AP device that it detects. Try scanning your RT-AC66U's 5ghz band using the various channels you are having difficulty with in order to determine if the issue is caused by the location of the client or the router, or both. At least it will either confirm or disprove what you've been seeing with other tools. Just a suggestion.
 
Spent some time today trying to further characterize the issue. I had always had the Bandwidth in 20/40/80Mhz, paying no attention to it until jeg, you mentioned your 5G setting stable at 80Mhz, which prompted me to try some things.

Here is what I found today.



Interesting that for the suspect channels (149, 153, 157, 161), that any setting above 20Mhz is unstable and turn on and off aperiodically, usually seconds at the 20/40/80 and 80 setting, and maybe up to a minute for the 40Mhz setting on those channels.

(Along with the 2.4G channels, the lower 5G channels and 165 were stable at any Bandwidth setting, although you cannot select 40Mhz or 80Mhz for channel 165)

No idea of this architecture but maybe a freq or clock multiplier or something?

Strange pattern. Probably a no-brainer for an ASUS engineer armed with the evidence, but I'm not smart enough to know firmware/nvram or an actual hardware issue.

Interested in any other thoughts, observations, experiences or tests...
 
New RT-AC66U - no signal or SSID detected on 5G?

Hi guys!

I got a new RT-AC66U last week, to provide 5G connectivity for game streaming on the Nvidia Shield my son is getting for Christmas. This router was recommended by Nvidia for this purpose.

I loaded the latest ASUS firmware (3.0.0.4.376_3602-g4e8bfd6) and configured it with separate (unique and not hidden) SSIDs on 2.4GHZ and 5GHZ all using WPA2-personal with AES. The 2.4GHZ Wi-Fi network works great, but the SSID for the 5G network is never detected by the Shield - or the several other dual-band Wi-Fi adapters I have in other computers in the house. Yes, the 5G radio is "on" according to the web display and indicator light - but no 5G signal can be detected, even sitting right next to it.

I've tried changing the 5G channels, bandwidth, security (open), etc. many, many times (as suggested by some of the previous posts, including with both hard and soft reboots) with no change in the missing 5G network - no 5G SSID or signal is ever seen by any dual-band adapter looking for it.

If I manually configure the 5G SSID into the Nvidia Shield, it reports that it has no bars at all and is "out of range" even when the Shield is 2 feet away. (The router's traffic monitor never shows a single packet in the 5G band either). I know that the Shield (and the other computers I've tested this with) are scanning correctly, since they show a handful of other Wi-Fi networks (no telling what band they're on) in my neighbor's houses (mostly weak signals).

The router's antennas are all attached o.k. (I get full bars on the 2.4GHZ network anywhere in the house), Tx power set to 100% - so aside from goofed up firmware or a defective transmitter - I don't have any further theories about the cause of this problem. This is all set up in a single family house, not in an RF noisy environment.

Anyone ever heard of the 5G radio not working at all, when everything else seems to be working perfectly? At this point I've run out of things to try and any suggestions would be most welcome. Hate to send it back, but am running out of options. I have contacted ASUS support, but have not heard anything back from them yet.

Thanks for any assistance you can provide!
 

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