Buffalo AP randomly becomes unresponsive

[bmittleider]

I have eight Buffalo WHR-HP-G54 units flashed with DD-WRT (v24-sp2 std) and three out of the eight will randomly stop responding to network traffic. When they become unresponsive I am unable to ping or connect to the web gui. Clients can see the AP but get no IP when connecting. If a client is connected when the AP becomes unresponsive the connection drops and displays the x on the connection status (Windows 7). In my troubleshooting I thought maybe the problem was coming from multiple connects/disconnects over the course of the week so I created a cron to reboot each AP every morning before any clients attempt to connect but that didn't seem to help. Unplugging the network cable to the AP and reconnecting it will bring connectivity back and it will work until it randomly quits again. Same goes for unplugging the power and rebooting the AP. All eight AP's were flashed at the same time with the same firmware and have been in place for over two years before this problem arose. I have replaced cables and changed ports to where the AP makes the connection back to the core router/switch but that has not changed anything. I thought I would ask around before I reflashed the AP's or replaced them. I know it's not impossible that three units could be bad, but I find it odd that they all lasted the same amount of time before failing so I have to believe it is software or a load issue.

 

Any thoughts?

[Mehmet]

I have eight Buffalo WHR-HP-G54 units flashed with DD-WRT (v24-sp2 std) and three out of the eight will randomly stop responding to network traffic. When they become unresponsive I am unable to ping or connect to the web gui. Clients can see the AP but get no IP when connecting. If a client is connected when the AP becomes unresponsive the connection drops and displays the x on the connection status (Windows 7). In my troubleshooting I thought maybe the problem was coming from multiple connects/disconnects over the course of the week so I created a cron to reboot each AP every morning before any clients attempt to connect but that didn't seem to help. Unplugging the network cable to the AP and reconnecting it will bring connectivity back and it will work until it randomly quits again. Same goes for unplugging the power and rebooting the AP. All eight AP's were flashed at the same time with the same firmware and have been in place for over two years before this problem arose. I have replaced cables and changed ports to where the AP makes the connection back to the core router/switch but that has not changed anything. I thought I would ask around before I reflashed the AP's or replaced them. I know it's not impossible that three units could be bad, but I find it odd that they all lasted the same amount of time before failing so I have to believe it is software or a load issue.

 

Any thoughts?

 

How many clients are connected to each of the devices? Do you experience this at quiet times also? Are the access points configured with static IP addresses?

[bmittleider]

How many clients are connected to each of the devices? Do you experience this at quiet times also? Are the access points configured with static IP addresses?

 

The AP that has the most problems typically has 5-8 devices connected to it throughout the day. It seems as though it is at random times and sometimes it works throughout the day and then the next morning it is in its unresponsive state. I have scheduled through a cron to reboot the routers twice a day but it seems as though when they become unresponsive they don't execute the cron or I would think they would be functional. They do have static IPs assigned and have since being installed.

[Mehmet]

The AP that has the most problems typically has 5-8 devices connected to it throughout the day. It seems as though it is at random times and sometimes it works throughout the day and then the next morning it is in its unresponsive state. I have scheduled through a cron to reboot the routers twice a day but it seems as though when they become unresponsive they don't execute the cron or I would think they would be functional. They do have static IPs assigned and have since being installed.

 

You mentioned that when this happens you are unable to ping or access the web interface of the access points... is that from all devices in the network? For example, are you able to ping or access the web interface from a device which doesn't connect wirelessly?

[tom_newton]

I've got one of these at home, and sometimes the windows host will only get an APIPA address from the upstream dhcp server, but setting a static IP (or using android) works.. a restart fixes that, too. Roughly monthly for me. Wonder if they're part of the same class of problem. I CAN get on the web UI from wired when this happens though.

[SYNACK]

Hav you recently introduced more Windows Vista/7 clients with IP6? We had a stack of APs that went totally postal when we migrated the first few over and totally ferral when we migrated more. It was just messy implementation in the software so maybe a firmware upgrade to a later version.

 

On the hardware side they are just consumer level devices so will have limited memory and limited quality internals and cooling. Its quite possible that three of them are just on the way out, especially if the power is a little dodgey. Have you tried swapping the power adapter from a stable one to a dodgey one, it could even be just that as these - power adapters - are usually manufactured for tiny sums to very questionable quality.

[ricki]

Hi

 

Are you having power surges. We had to put ours on an ups and that stopped it playing up and loosing settings.

 

Richard

[bmittleider]

You mentioned that when this happens you are unable to ping or access the web interface of the access points... is that from all devices in the network? For example, are you able to ping or access the web interface from a device which doesn't connect wirelessly?

 

I have tried from multiple devices wireless and wired from the network and am still unable to ping/http into the router.

 

Hav you recently introduced more Windows Vista/7 clients with IP6?

 

Haven't introduced any new devices but re-imaged a few since the install of the APs. However we do not use IP6 anywhere.

 

Hi

 

Are you having power surges. We had to put ours on an ups and that stopped it playing up and loosing settings.

 

Richard

 

Not all of the troubled devices are plugged directly into a ups or surge protector but the one that has the most problems is plugged directly into an APC 1000 unit.

[SYNACK]

Haven't introduced any new devices but re-imaged a few since the install of the APs. However we do not use IP6 anywhere.

 

It is still enabled by default and will use it in the background unless you disble it, that was enough to set ours off.

 

Have you tried a different power adapter, even protected by a UPS those adapters are a major weakpoint.

Edited April 4, 2012 by SYNACK

[ricki]

Have the kids found the wifi kill app

 

Richard

[ricki]

HI

 

Have the access points got the latest firmware.

 

Support - Downloads | Buffalo Technology

 

Richard

[chazzy2501]

Try disabling a few features like WMM (old intel cards dislike this) any Manufacture specific turbo stuff, allow only a long preamble & disable b support if you don't need it.

 

See if you can set up a log server, then you may see if any weird things are happening before it fails. Also telnet is your friend see if you can telnet in (before it crashes), if it does I'd bet its got more options than the web interface.

 

If none of that works check the antennas are correctly connected (may cause radio to over heat) and finally reduce the output by half to see if it is cooking itself.

Edited April 5, 2012 by chazzy2501

[bmittleider]

It is still enabled by default and will use it in the background unless you disble it, that was enough to set ours off.

 

Have you tried a different power adapter, even protected by a UPS those adapters are a major weakpoint.

 

I have replaced the power adapter to the ap that has been acting up the most. I will have to monitor it for a week or two to really know if it did anything. I also started disabling IPv6 on all our faculty laptops to see if it has any effect. I will only make these two changes and monitor it now for awhile to see if any change.

 

Have the kids found the wifi kill app

 

Richard

 

It's not impossible that they found/used it but with the timing of the outages so random and even during the times students are not present I am leaning towards it not being the cause.

 

HI

 

Have the access points got the latest firmware.

 

Support - Downloads | Buffalo Technology

 

Richard

 

All the ap's have been flashed with DD-WRT over the stock Buffalo firmware.

 

Try disabling a few features like WMM (old intel cards dislike this) any Manufacture specific turbo stuff, allow only a long preamble & disable b support if you don't need it.

 

See if you can set up a log server, then you may see if any weird things are happening before it fails. Also telnet is your friend see if you can telnet in (before it crashes), if it does I'd bet its got more options than the web interface.

 

If none of that works check the antennas are correctly connected (may cause radio to over heat) and finally reduce the output by half to see if it is cooking itself.

 

I will start by setting up a log server to monitor the units and see if I can pinpoint when and what is going on. Thanks for the suggestion. If I continue to see the problem after changing a few settings from the previous posts I will then try reducing the output.

[ricki]

HI

 

I had problems with flashing a buffallo a few years ago and had to resort to putting the buffalo firmware back. But if you need to keep it for a reason you need to eliminate the the firmware as the problem. There are several versions of linux that can do this 7 alternative firmware for wireless routers - Instant Fundas but please note you can birck your device. The other thing I have seen do this is if they are over heating. Plus have you considered sniffing the traffic on your network and analysis the results with something like the free version of Real-time portable network analyzer, Sniff Packets and Analyze Protocols, Free Trial - Colasoft

 

It can show you allsort of things like conflicting ip addresses and nic cards spamming the network which could cause the nic on the access point to crash and stop working and this would be random.

 

Richard

 

Richard

[SYNACK]

If IP6 does turn out to be the cause your long term solution is not turning it off but replacing the APs with something a bit more robust. IP6 is going in everything now and some do not have the option to fully turn it off.

[tom_newton]

No v6 on wireless on my windows boxes - but (unused) wired connections had it until 2 mins ago.

[SYNACK]

No v6 on wireless on my windows boxes - but (unused) wired connections had it until 2 mins ago.

 

Two minutes ago, why. If you turned it off your just killing an extra layer of network robustness. Windows systems will quite happily do stuff over IP6 when is bails on IP4 like connections to resources over a VPN with the same IP4 domain as it can just go over IP6.

 

Turning it off just to keep some old junk working is just posponing a problem not solving it.

[Arthur]

Just to add to what @SYNACK said about IPv6...

 

Q. What are Microsoft's recommendations about disabling IPv6?

A. It is unfortunate that some organizations disable IPv6 on their computers running Windows 7, Windows Vista, Windows Server 2008 R2, or Windows Server 2008, where it is installed and enabled by default. Many disable IPv6-based on the assumption that they are not running any applications or services that use it. Others might disable it because of a misperception that having both IPv4 and IPv6 enabled effectively doubles their DNS and Web traffic. This is not true.

 

From Microsoft's perspective, IPv6 is a mandatory part of the Windows operating system and it is enabled and included in standard Windows service and application testing during the operating system development process. Because Windows was designed specifically with IPv6 present, Microsoft does not perform any testing to determine the effects of disabling IPv6. If IPv6 is disabled on Windows 7, Windows Vista, Windows Server 2008 R2, or Windows Server 2008, or later versions, some components will not function. Moreover, applications that you might not think are using IPv6—such as Remote Assistance, HomeGroup, DirectAccess, and Windows Mail—could be.

 

Therefore, Microsoft recommends that you leave IPv6 enabled, even if you do not have an IPv6-enabled network, either native or tunneled. By leaving IPv6 enabled, you do not disable IPv6-only applications and services (for example, HomeGroup in Windows 7 and DirectAccess in Windows 7 and Windows Server 2008 R2 are IPv6-only) and your hosts can take advantage of IPv6-enhanced connectivity. (Source)

Edited April 6, 2012 by Arthur

[tom_newton]

I count the windows box as "keeping some old junk working"

 

Just want to see if it helps the AP's stability. My natural curiosity to mess. I doubt it will have any effect - the wired netwrok isnt used, but we'll see.

[SYNACK]

I count the windows box as "keeping some old junk working"

 

Just want to see if it helps the AP's stability. My natural curiosity to mess. I doubt it will have any effect - the wired netwrok isnt used, but we'll see.

 

Yea, thats my view on the APs, some old dirty *nix junk, Windows of any version does not trash itself when exposed to IP6. It took some time but they have fixed in newer devices. What kind of AP are you having issues with? The ones that really hammered it home for use were TP-Link and a few older netgear ones that just went mental when exposed to IP6.