Wireless help desperately needed!

[Neptune]

Hope someone can give me some good pointers!!!

 

We have setup 4x Wireless access points in a very small school and the problem is that the laptops can just loose the wireless connection for absolutely no reason, maybe 10-15 minutes after starting up - No access to LAN or Internet, but fine until that point. It's completely random as to what laptops it happens to and how many and often even at different points in the school.

 

Here's the school setup

PHYSICAL

- Old building with thick walls

- Neighbouring houses with wireless

 

NETWORK/LAPTOPS

- NO server - Peer to peer laptops only - NO DHCP server

- All Windows XP laptops

- Static IP addresses on each laptop

 

WIRELESS

- 4x Netgear WG103 WAPs

- Located throughout school, channels seperated from each other and neighbouring houses

- Using 802.11b wireless

- WPA-PSK2 encryption

[catch21]

What does the underlying switched network look like? Are you sure no one has connected anything else onto the network without your knowledge?

[CHR1S]

Power settings? Possibly turning off WiFi to save power.

 

Very poor roaming, on the edge of two channels?

 

b wireless is 2.4GHz, is there an intercom, or cordless phone, maybe a microwave?

[Neptune]

All the network points in the school go back to a single unmanaged switch - The WAPs are plugged in in the classrooms. Apart from a NAS box and a photocopier, nothing else is attached to the network.

 

The big problem is, everything works fine when I'm at the school, when I leave things go wrong!!!! Is there any free software or anything I can do to log the issues?

 

I have checked power saving and don't think the wifi is turned off to save power. Where shouldI be looking, in case I've missed something?

 

No intercom in school, but yes to Microwave & Cordless phone... Any thoughts, etc??

[CHR1S]

Pick up a laptop and wander round, find the spots where its low signal and where you think you are in between two or three access points to see where and if they drop out.

 

In the wireless cards properties there will be sections for power management and possibly roaming aggressiveness.

Do you use zero config or driver clients to configure your wireless on the laptops?

 

While your wondering, make a phone call on one of the handsets and warm up your coffee in the microwave and see if they are responsible

[foofighterjim]

If you are using 2.4GHz AP, have you made sure the channels are set properly? The only non-overlapping channels on this frequency are 1, 6 & 11. You should not have two adjacent AP's on the same channel. If the school has motion detection sensors for the alarms these also tend to interfere with channel 6 (most commonly) albeit only in the area immediately around the sensor.

 

If you have an XP laptop you could try Netstumbler. This will also help if there are houses nearby that may also be conflicting.

Edited November 12, 2013 by foofighterjim
Additional info

[twin--turbo]

you don't say how many laptops.

 

Rob

[chazzy2501]

I assume that the laptop wifi cards are old as you're using 802.11b only. Some old wifi cards hate even seeing WMM (The old intel 2100 will crash) so disable that option on the APs. Also make sure that long and short preamble is available. You could force the APs into B only mode to ensure compatibility.

 

Even more work, but I'd do it, would be to reduce the security to WPA away from WPA2 as I don't think it's properly supported by 802.11b... (WPA uses the same kit as WEP did)