A little context: a local school district has several campuses. At least at one particular campus there is an issue with computers staying connected to an enterprise grade 802.11n wireless LAN, particularly with Windows XP systems but possibly with all other OSes (Win 7, OS X). A lab with ~30 computers will have one computer at any given time without a functional wireless connection, usually it can be manually reconnected in the usual way rather quickly. There are two access points (cisco models of some type that look like UFOs) near the room of one particular lab that seems to most frequently encounter issues.

While easy to fix an individual connection, the school in question is totally devoid of any technically capable personnel no their staff, so any time one computer loses its connection they stick a sign on it indicating that the internet is broken on that computer and leave it until a technical personnel from the district can come on-site to address it.

It doesn't seem reasonable to me that any devices should be losing their connection, with enterprise grade equipment that's capable of supporting high volume installations. The desktop people blame the network, the network people blame the desktop configuration. Seems like the easy solution is to enable full logging on the APs and carefully track what devices are losing their connections and why; it's impossible to predict which desktop computers might temporarily lose their connection and enable logging there; they'd all need logging, and then we'd have to have someone on-site to check the logs on each one when it loses its connection (because it can't be remoted into once the connection drops until someone manually reconnects it to the wireless network.)

It seems like maybe 5 devices an hour out of 150 experience this issue.

Anyone have familiarity with wireless networking in terms of how to best resolve this? Other sites have similar configurations and aren't reporting the same degree of issues.

The biggest problem is that these computers in labs are used for student testing; and if the connection drops during a testing session the kid basically loses their test.

Obviously using wired connections would be ideal but is not an option due to the mechanical costs of installing that many circuits in this old building.
g=

No ideas to help you, but not surprised by the problem. At our campus they decided to go to wireless for almost all student dorms and for their laptops when using them elsewhere on campus. It is a so called "enterprise wireless solution" and there are continual problems with connections being dropped or being refused in the first place. I get to deal with it all the time at work. At any given time, especially during busy periods, there will be at least a couple of the 50 laptops we lend out returned with a comment that they will not connect to the internet. Our systems guys have talked with the campus IT guys and no solution has been offered. In any case, after several hours they will start connecting again.

wired

Do you know what model APs are in use at the school?

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RIP, Greg the DogSitter. You are missed.

if they're desktop machines then you could wire the machines within the same room to an access point. 1 wireless signal instead of 30.

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I may start an argument with this statement, but in my opinion as a schools "tech guy"... Wireless is NOT RELIABLE ENOUGH for environments where non-tech people will be using computers.

In my experience, and in the experience of a couple other school tech people I've talked to (this conversation came up just a couple weeks ago at a meeting, in fact), dropped wireless connections are "perfectly normal" and essentially impossible to stop.

You have two options;
Train the staff at the school that it's not the end of the freakin' world when a connection drops, and show them how to fix it on the fly... or;

Go WIRED connections for labs and other spaces where it's practical.


If you really WANT to try and troubleshoot the problem, I'd start by changing the channel the access point uses.. in case there is some local interference ( like a *&$# gate opener right next to the mother%*#@*NG lab which keeps #$)@ing up a wireless bridge I spent four months troubleshooting... for example.... Changed the channel, problem went away!).

Hope this helps!

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Paul F.
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Persistence is necessary for Excellence. And Persistence is a Decision.
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Paul F.
I may start an argument with this statement, but in my opinion as a schools "tech guy"... Wireless is NOT RELIABLE ENOUGH for environments where non-tech people will be using computers.

I think the only people you'd start an argument with are the proponents of wireless everywhere.

Unfortunately in my experience with older buildings especially the quick fix to get networking on-site always seems to be to throw up a few APs and ignore the occasional dropped connection. As far as I'm concerned that works for most use cases, but if you're actually doing student testing online, any loss of connectivity is simply not acceptable. It's tremendously unfair to the student with the device experiencing the issue, as it often forces them to restart their exam. (A lot of testing software is rather esoteric and attempts to lock down the computer to prevent cheating by checking google for answers... never mind that these days the kids probably have their own smartphones so only the watchful vigilant eyes of a human proctor will keep the kids honest.
g=

I'm no expert, but I think Paul F. is right. In our medical office (now closed) I had about 15 wired desktops (Dells and a couple of IBMs) and three wireless Fujitsu tablets (the convertible notebook kind, not the keyboardless kind that Apple and others make now), which connected via a SonicWall wireless VPN router. I was constantly getting calls that "The SonicWall is down." I could restart it remotely, which sometimes worked, but often I had to drive out and power cycle the router. Finally, I just put it on a power strip with a sign explaining how to turn off the SW, wait 30 seconds, and turn it back on.

I will say that at WHRB, which uses a wireless system installed and maintained by Harvard IT (I assume), the connections seem pretty solid. I see undergraduates working on laptops (mostly Macs, BTW) and never hear complaints about dropped connections. But then, I'm only there for a few hours once a week.

Gabester, it is not hugely expensive to run Ethernet cables above dropped ceilings, if they have them, and then drop them down the walls—or just run surface-mount conduits for cables everywhere (paint them the same color as the walls, and nobody notices them). If you need to get to tables in the middle of a room, you can use poles dropped down from the ceiling to a multiport switches.

If the school has a PTA or some such organization, you can probably recruit volunteers to do the work. Just get someone from the district to supervise (assuming they won't hit you all sorts of bureaucratic crap). Once all the computers are wired, the problems will be solved.

Now what the schools do that are handing out wireless laptops, I don't know.

/Mr Lynn

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gabester

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Paul F.
I may start an argument with this statement, but in my opinion as a schools "tech guy"... Wireless is NOT RELIABLE ENOUGH for environments where non-tech people will be using computers.

I think the only people you'd start an argument with are the proponents of wireless everywhere.

Unfortunately in my experience with older buildings especially the quick fix to get networking on-site always seems to be to throw up a few APs and ignore the occasional dropped connection. As far as I'm concerned that works for most use cases, but if you're actually doing student testing online, any loss of connectivity is simply not acceptable. It's tremendously unfair to the student with the device experiencing the issue, as it often forces them to restart their exam. (A lot of testing software is rather esoteric and attempts to lock down the computer to prevent cheating by checking google for answers... never mind that these days the kids probably have their own smartphones so only the watchful vigilant eyes of a human proctor will keep the kids honest.
g=

No argument from me either. Here at the campus the main reason to go wireless is the expense of upgrading the wired infrastructure. Much of it is Cat3 pulled into all rooms of all buildings about 20 years ago as part of the installation of a digital PBX to replace an older phone system. Cat5 and better cables were installed in new buildings built since then, where needed for network expansion, or installed as part of a renovation. The administration pushes the "improved access" line, the techs who actually have to deal with the problems are "encouraged" to keep their mouths shut.

Every room with more than one AP, divide up the channels like Paul F. said.

If they truly are "Enterprise" grade AP's, they are dual band. If the computers all have dual band adapters, someone should be able to figure out how to assign computers between 2.4 GHz and 5 GHz so they never drop connections.

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in tha 510.

Tell the IT guys to shorten the DHCP leases to a half hour and split the address range so that two-thirds the addresses are served from a primary DHCP server and the rest from a secondary DHCP server.

Uhm... one of the common problems even with 'enterprise class' wifi is that you're normally limited to a number of attached clients. There's only so much you can set up before the aether is so clogged that more connections fail. I believe most of them are defacto limited to between 15 and 20.

Chakravatian's solution is quiet likely a good one, but a more robust solution will be to measure and either reduce your wireless load or increase the number of access points.

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cbelt3
Uhm... one of the common problems even with 'enterprise class' wifi is that you're normally limited to a number of attached clients. There's only so much you can set up before the aether is so clogged that more connections fail. I believe most of them are defacto limited to between 15 and 20..

Correct. This is why I asked for info on the specific model in use; more recent AP models can handle more users.

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RIP, Greg the DogSitter. You are missed.

My work wifi is miserable. My MBP can only get a decent Internet connection half the time, but I have a decent signal everywhere. This is a software issue.

And yet, I've set up ad hoc classrooms with original apple airport hubs and had no problem.

The issue can be both hardware and software. Seems like a combination of both going on.

I wold definitely wire several more machines. Maybe one more wifi hub would go along way.