Can't connect to 2.4G, please help.

[ricardjs]

Hi all.

The problem is as described, and is very strange, as you'll be able to see:

Tested with 3 routers: Asus RT-AC66U (2) and RT-16N
All had the latest asus firmware; All were reset to factory defaults after the update and configured manually.

Problem, can't connect to 2.4G: Or I'll receive an authentication error or, the standard message that couldn't connect to the network. Sometimes, if i restart the router, i will be able to connect for a few seconds to a few minutes and eventually the link starts to be slower and slower untill i even couldn't connect anymore.

The signal is excellent, the noise floor is arround -90db, i'm isolated on channel one with only one network competing but with a very low signal that sometimes it's even undetected.

Now the confusing: An RT-N16 worked there for 2.5 years without issues using same channel and 40MHz bandwidth; then we upgraded to the RT-Ac66U that also worked perfectly on the same settings for a little over a year.

Since about 2 weeks ago, no client could connect anymore. Everything is great on the 5G...

I thought initially the router was defective and bought a new RT-AC66U (the second); after updating the firmware, reset and configure, i notice the same issue! I thought first it was interference from other networks, but no...

Then i thought about interference from cordless phones, but the ones there are the same that have been for the past 4 years, there was no new hardware there that wasn't before.

If i bring the routers to my home, all of them work great; if i reset them, they work great for a couple of minutes... when i'm about finishing to putt all the fixed DHCP adresses (it's a company with about 24 devices from which about 10 are wireless), no device can connect anymore.

The logic, i know, is it's some sort of interference there... BUT: I have an old dlink DWL-2100AP that i installed there for testing pourposes, and it works great! (also reports a very low noise floor and excellent signal).

Any ideas on this?

Thanks.

 

[ricardjs]

To add some more info, that i believe that helps prove that it is not interference: Everytime i reboot the router i can (as mentioned above) connect to any of the ip cameras and see the transmission, that with seconds, sometimes minutes, start to be slower untill the cameras disconnect.

Thanks for your time.

 

[coldwizard]

Wild guess - you updated from a version of firmware before Dec 2014 on the Ac66Us?

There was an issue about that time where dnsmasq would run out of available leases if you had a
very small DHCP pool combined with many out-of-pool reservations.

 

[coldwizard]

Since 40Mhz uses most of 2.4 channels, try changing to 20Mhz and fixed a channel number 1,6,or 11.

If that works, then the DHCP problem I mentioned does not apply.

And if that works, it may mean that the one competing network is just close enough to spoil the 40Mhz.

 

[ricardjs]

Since 40Mhz uses most of 2.4 channels, try changing to 20Mhz and fixed a channel number 1,6,or 11.

If that works, then the DHCP problem I mentioned does not apply.

And if that works, it may mean that the one competing network is just close enough to spoil the 40Mhz.

Thanks for you answer. Reducing the bandwidth to 20 MHz was the first thing i tried, the result was the same...

Can you please elaborate on your other option (dnsmask) and how to try a fix?

Thanks again for your help!

 

[coldwizard]

The quickest fix/check would be to install the older firmware that was working.

Here is how the dnsmasq flaw failed.
You would have assigned a small DHCP pool say from .21-.30 (10 IP addresses. Then you statically via DHCP assign addresses to .101-111 (11 IP addresses not in the pool). Dnsmasq expects to handle 10 addresses (pool size), but now has 21 addresses to manage. The first 10 machines connect ok, but after that no more can connect. The fix is to increase the DHCP pool to include the static addresses. In my example, the the pool is set to .21-111. Now since all the managed addresses are in the pool it works.

But looking again at your messages I notice "Everytime i reboot the router i can (as mentioned above) connect to any of the ip cameras and see the transmission, that with seconds, sometimes minutes, start to be slower untill the cameras disconnect."
You already have a connection and IP address so I now don't think that dnsmasq could be the problem.

 

[ricardjs]

Yes, i also don't think so, because, as you say, my address pool is covering all addresses freom 192.168.1.2 to 192.168.1.254

I think it may be firmware related, as all RT-N16 and RT-AC66U behave the same...

Also, using just wireless G or N could make a difference? I mean, the Dlink just uses G and all Asus are using N... should that make a difference.

I also noticed some user here sayng the only way to fix some issue (related to CFE i believe) was to put the router in emergency download mode and upload the new firmware... Is that worth trying? (this is a company and everytime i fiddle with the router i have eveyone on my a$$!!)

Also, someone else more ideas on where to look to?

Thanks

 

[coldwizard]

Did you try reverting to an older firmware? With two AC66 units you could configure one fully with different SSIDs and older firmware. Then only be down for the time to rename the SSIDs and swap units.

Update -07 of Johns fork of Asuswrt-Merlin is older but stable if you are just using as a basic firewall/router.
http://www.snbforums.com/threads/fork-update-for-374-43-available.18914/
Download link to all versions is on first posting. Select the small box in the version you want and download the zip file from top menu of "One Drive".

 

[ricardjs]

I see he has and RT-16N firmware, i will try on that one first and see how it goes...

Thanks for the help!

 

[ricardjs]

I tried version 7 and 8, same results... i will try to install merlin's on the AC66...

 

[coldwizard]

If update 07 did not solve the 2.4Ghz problem at 20Mhz bandwidth, then I doubt it is a firmware issue. Problem has to be something else.

 

[ricardjs]

I understand what you say and even would agree if it was not for the fact that i put there the DLINK AP (only G mode) and it works flawlessly!
I installed the latestMerlin's on the RT-AC66U and the results were almost the same, it was a little better in the way that it actually worked good for 10 minutes (before it was about 2-3 minutes)... We do have a Lenovo laptop that connected very good on this last Merlin's firmware, but this morning (after the router was all night on) allready didn't... This is also interesting, because the other laptops could never connect. The IP cams were able to connect for those 10 minutes.

Will also test another router i have, that one works on N speed.

 

[ricardjs]

Update:

The modem we have working is a modem router Technicolor. We untill now have had it in bridge mode and with wireless off. For testing, i enabled the wireless. All equipments connect to it without issues...

 

[ricardjs]

Another update:

It is definitly the Asus software.

Following something i read here, I decided to do a recovery of the RT-16N, and witout any configuration, just try to use it.

Guess what, it's working flawlessly!

The reason i say it is on the software it is because the issue was replicated in all 3 routers. I will now try to add settings one by one and see how it goes...

The only think unusual on out config here is that we are about 25 clients, some with fixed IP, some with fixed DHCP, some with DHCP. We have about 15 entries in the fixed DHCP.

 

[RMerlin]

Considering the fact that Asus probably sold hundred of thousands of routers over the years, it's highly unlikely that a software issue is causing what you describe, otherwise it would imply that none of those thousands of users would be able to use the 2.4 GHz band. There is therefore something specific to your environment causing issues. With so many clients (you talk about 25 clients here), I would start by looking for one particular client causing issues when that particular client connects, or actively transfers data. Wifi being shared, one single client can impact every other client connected to the same band. Could be a defective adapter emitting noise or garbage, a broken wireless driver, something sending a broadcast storm, etc...

(side story: a few weeks ago, I spent the afternoon at a customer's office trying to troubleshoot why he was randomly having major issues connecting to his NAS, over Ethernet. Turns out the problem was caused by one specific PC that, once I disconnected it from his network, his entire network became 100% stable. Plug it back, and within 2 minutes there were a lot of packet losses on his whole network. That's one concrete example to support my theory here that your problem can very well be caused by one of your clients).

Also, the 2.4 GHz band is overcrowded. That particular frequency see interference coming from wifi routers, wireless mices, baby monitors, microwave ovens, old cordless phones, Bluetooth devices, USB 3.0 devices, and the list goes on. You will have to start by isolating things.

Also, do your test with one specific channel rather than Auto mode, and set it to 20 MHz. Getting 40 MHz to work reliably on the 2.4 GHz band is nearly impossible in 2015, unless you live somewhere in the woods.

 

[ricardjs]

Thank you for your attention and advice.

For all testing i allways used 20MHz at a fixed channel. Channel 1 has no overlapping, but it is interesting to note that channel 6 presents less noise (even though it has 2 networks there overlapping).

I also supected a bit what you say, from the tests i ran yesterday. All routers work great after a reset and no configuration (except for wireless) and connections. I can configure it even for 40MHz and get a 50 Mbits transfer rate!! The problem comes after i start to configure static ips on the dhcp menu or, when at the same time i start to connect devices. This is what i will try to figure out on monday...

Will keep posted, thanks all for the help so far!

 

[hiac]

I encountered same issue, I wonder if you have resolution?