Wireless Wierdness

Situation;
Wireless Router and several Range Extenders installed in a 30 room hotel.
All working on Channel 3.
Suddenly, Channel 3 disappears(?) and the router / repeaters cannot be seen.
Tried a couple of Wireless 'sniffer' programs with no luck at all.

Solution;
Moved every device to Channel 8 and all working again.

For testing purposes, I moved some units back to Channel 3 and they disappeared again.

Does anyone have any ideas as to what might be going on?

Sounds like interference on channel 3 from non-wifi devices (analogue transmitters possibly?) without a spectrum analyser it is very difficult to say.

Don't have a spectrum analyser but, it must be a very 'tight' monster signal before it kills one channel completely and doesn't affect any others. I can't even 'see' a device if I'm standing right next to it.

My suspicion is that it may be a microwave cooker, given the likely spread of WPAs in a 330-room hotel, although of course, they are not on continuously.

If it is such, possibilities are in-

Kitchen/s

Bar - for snack meals

Bedroom - possibly temporarily with a guest (I have seen small microwave cookers, about one-third of the usual volume.)

===========================

Externally, remote monitoring equipment, possibly on a public utility.

Has anyone any idea of the frequencies used by (temporary) traffic lights for example?

I think that microwave cookers are out. It's a 30 room hotel, not 330 and, the problem started on Saturday and has been continuously present since.
It's as if a 'black hole' has appeared in the spectrum.

Have you got inSSIDer installed? It may show the signal there even if unusable. They also do a Spectrum Analyser - although not free.

You have only stated that you have tested channels 3 and 8.

Have you tested other channels?

Also I do not know that it is interference, that was a speculation based upon the information you gave and assumptions based on my own knowledge and experiences.

If you have further information on the channels that do, and do not work that would help narrow down the possibility's.

Also you say an access point and range extenders. Are they passive signal repeaters, wireless access points (with cabled connections to the network) or active wifi repeaters (eg WDS)?

Have you tested different channels for throughput?

Has anything changed recently (new building or road works in the area, new network devices, or software/firmware upgrades)?

Don't have inSSIDer installed but, I havea couple of others (NetStumbler etc.)

Will download a copy.

The only channel affected is Ch 3, all others are working.

Apart from the main router, all devices are active WiFi Repeaters (Not allowed to use wires athe the 'boss' "doesn't want to see any wires"

Throughput on every channel (except 3) seems to be 'normal' and, to the best of my knowledge, there has been no new building etc going on in the area.

There are, however, a number of other wireless networks in the vicinity and, all are 'visible'.

There is, as far as I can see, no other network using either ch3 or ch8 (which is why I chose them)

Completely baffled by the whole thing.

The latest version is no longer FREE but the older Version2 is perfectly good.