3com wireless ADSL router - stuck on channel 6 and can't connect

Hi all. Can't seem to find any help for this with Google.

I have a 3com Wireless ADSL router (this one:
http://www.3com.com/prod/en_UK_EMEA/...=3CRWDR100A-72)

It's been happily distributing my broadband connection round the house
for a month or two now (two of us access it from our laptops -- a Dell
with internal WiFi and an HP with a US Robotics PCMCIA card).

Yesterday, however, I stopped being able to connect wirelessly (it's
still fine by ethernet lead). I set it up on channel 3 before (from
reading this group, I realise 1, 6 or 11 would be better). But now it
refuses to leave channel 6 -- whatever I set it to, it's back on channel
6 within a few seconds.

I have tried anything I can think of -- including a factory reset and
restore of previously working settings, and disabling the WPA-PSK/TKIP
encryption it normally uses. No joy.

I also notice *two* new wireless networks in the area, at quite high
signal strength.

Can anyone suggest what might be going on?

On Mon, 13 Jun 2005 12:14:16 +0100, G <(E-Mail Removed)> wrote:

>I have a 3com Wireless ADSL router (this one:
>http://www.3com.com/prod/en_UK_EMEA/...=3CRWDR100A-72)
>
>It's been happily distributing my broadband connection round the house
>for a month or two now (two of us access it from our laptops -- a Dell
>with internal WiFi and an HP with a US Robotics PCMCIA card).
>
>Yesterday, however, I stopped being able to connect wirelessly (it's
>still fine by ethernet lead). I set it up on channel 3 before (from
>reading this group, I realise 1, 6 or 11 would be better). But now it
>refuses to leave channel 6 -- whatever I set it to, it's back on channel
>6 within a few seconds.
>
>I have tried anything I can think of -- including a factory reset and
>restore of previously working settings, and disabling the WPA-PSK/TKIP
>encryption it normally uses. No joy.
>
>I also notice *two* new wireless networks in the area, at quite high
>signal strength.
>
>Can anyone suggest what might be going on?

When you changed channels from 3 to 6, the two new networks appeared
because your site survey tool on the router only checks the channel
for which it's set. Very few people use channel 3, while channel 6 is
the most popular default channel. Channel 3 is a bad choice because
it overlaps channels 1 and 6, thus creating and getting interference
from both.

The most porbable reason you're "stuck" on channel 6 is that the
browser cache on your PC is reading pages from the cache instead of
from the 3Com router. Empty the cache, force a refresh (hold down
shift key while hitting refresh), temporarily set the cache size to
zero, *OR* temporarily set the browser cache to always read a new
page. If you suspect your browser is acting oddly, I suggest you
check for spyware.

"Stopped being able to connect wirelessly" is a very vague description
of some kind of problem. If you need help with this, please supply
some detail, such as the exact failure and any error messages.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558

Jeff Liebermann wrote:
> On Mon, 13 Jun 2005 12:14:16 +0100, G <(E-Mail Removed)> wrote:
>
>
>>I have a 3com Wireless ADSL router (this one:
>>http://www.3com.com/prod/en_UK_EMEA/...=3CRWDR100A-72)
>>
>>It's been happily distributing my broadband connection round the house
>>for a month or two now (two of us access it from our laptops -- a Dell
>>with internal WiFi and an HP with a US Robotics PCMCIA card).
>>
>>Yesterday, however, I stopped being able to connect wirelessly (it's
>>still fine by ethernet lead). I set it up on channel 3 before (from
>>reading this group, I realise 1, 6 or 11 would be better). But now it
>>refuses to leave channel 6 -- whatever I set it to, it's back on channel
>>6 within a few seconds.
>>
>>I have tried anything I can think of -- including a factory reset and
>>restore of previously working settings, and disabling the WPA-PSK/TKIP
>>encryption it normally uses. No joy.
>>
>>I also notice *two* new wireless networks in the area, at quite high
>>signal strength.
>>
>>Can anyone suggest what might be going on?
>
>
> When you changed channels from 3 to 6, the two new networks appeared
> because your site survey tool on the router only checks the channel
> for which it's set. Very few people use channel 3, while channel 6 is
> the most popular default channel. Channel 3 is a bad choice because
> it overlaps channels 1 and 6, thus creating and getting interference
> from both.
>
> The most porbable reason you're "stuck" on channel 6 is that the
> browser cache on your PC is reading pages from the cache instead of
> from the 3Com router. Empty the cache, force a refresh (hold down
> shift key while hitting refresh), temporarily set the cache size to
> zero, *OR* temporarily set the browser cache to always read a new
> page. If you suspect your browser is acting oddly, I suggest you
> check for spyware.
>
> "Stopped being able to connect wirelessly" is a very vague description
> of some kind of problem. If you need help with this, please supply
> some detail, such as the exact failure and any error messages.
>

Thanks very much for taking the time, Jeff. I now understand why not to
use channel 3 and will switch to 1/6/11 (or even 13 -- I'm in the UK).

I've been using the US Robotics (USR) WiFi card admin tool, on which the
'Site Survey' screen shows (I think) available networks across all
channels. So I think the other networks probably *are* new, though I'm
not sure if this is relevant.

I don't think the problem is with the browser caching the router's admin
screens -- the first thing I know of the channel switching back to 6 is
when I see it listed that way on the Site Survey screen of the US
Robotics tool. Also, I can switch the router to any channel I like if
the wireless feature is disabled, and it keeps showing that way on the
admin screens. However, as soon as I re-enable wireless, it flips back to 6.

As to the exact nature of the connection error -- I'll see if I can get
an error message out of it when I'm back home tonight, but in general I
see my network listed, click on it and click 'Connect'... and nothing
happens. It says 'Connecting...' for a few seconds, then gives up and
starts 'Scanning...' again. The basic problem is that I can't get a
connection at all -- I get the Windows network connection icon at the
right of the taskbar with a red X on it.

Will report any progress... in the meantime, any more help gratefully
received.

George

On Mon, 13 Jun 2005 17:31:47 +0100, G <(E-Mail Removed)> wrote:

>>>I have a 3com Wireless ADSL router (this one:
>>>http://www.3com.com/prod/en_UK_EMEA/...=3CRWDR100A-72)

>I've been using the US Robotics (USR) WiFi card admin tool, on which the
>'Site Survey' screen shows (I think) available networks across all
>channels. So I think the other networks probably *are* new, though I'm
>not sure if this is relevant.

The "site survey" tools for the access point and the clients are quite
different. The way infrastructure mode works is that the access point
sits on a fixed channel number. The client radio scans all the
channels looking for a matching SSID. When it finds the SSID, it
stays on that channel. The access point "site survey" is only
interested in other access points on the same channel it's sitting
upon.

>I don't think the problem is with the browser caching the router's admin
>screens

It's been a problem for me on several occasions. Best not to make
assumptions and just clear the browser cache and see what happens.

> -- the first thing I know of the channel switching back to 6 is
>when I see it listed that way on the Site Survey screen of the US
>Robotics tool.

I'm guessing that's the site survey tool in the wireless client
(laptop). It takes quite a while to "expire" the connection in such
tools. I'm not familiar with the SMC incantation, but the Dlink and
Linksys flavors will list an access point long after it has moved to a
different channel, or you've driven out of range. Methinks it best
that you fire up Netstumbler on either the laptop or on a different
machine. It will show instantly if there is any connection or status
change. If this is too much trouble, then just change the SSID at the
same time you change channel and tell the SMC client to go hunting for
the new SSID. That should take care of any persistance.

>Also, I can switch the router to any channel I like if
>the wireless feature is disabled, and it keeps showing that way on the
>admin screens. However, as soon as I re-enable wireless, it flips back to 6.

I'll stand on my guess(tm) that it's browser cacheing. That's exactly
what my stupid BEFW11S4v4 was doing before I put the browser settings
back to normal. The screens for wireless enabled and disabled are
probably diffrent. When you switch back and forth, the browser
displays the cached version instead of getting a fresh copy.

>As to the exact nature of the connection error -- I'll see if I can get
>an error message out of it when I'm back home tonight, but in general I
>see my network listed, click on it and click 'Connect'... and nothing
>happens. It says 'Connecting...' for a few seconds, then gives up and
>starts 'Scanning...' again. The basic problem is that I can't get a
>connection at all -- I get the Windows network connection icon at the
>right of the taskbar with a red X on it.

The big X usually means that it's disabled. Right click and select
"enable". Of course, it's probably not something that simple.
There's probably a connection "profile" in the SMC client that's setup
to autologon to your access point. Probably, some of the settings
have changed. If there's such an animal, try deleting and recreating
the connection parameters. If you can "see" the access point with the
SMC client utility, then you should be able to connect. Also, try it
without encryption to simplify testing. Then turn the encryption back
on again.


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558

Well, I tried Network Stumbler and it did show similar things to the USR
site survey tool.

Anyway, I did a factory reset on the router and 'upgraded' it with its
existing firmware, then restored all the settings manually.

It now seems to be stuck on channel 4 instead, but I can connect again,
so for now it seems fixed. Not ideal, because there's presumably some
interference with a local network on channel 7, but never mind.

Thanks again for your help.

On Fri, 17 Jun 2005 10:05:50 +0100, G <(E-Mail Removed)> wrote:

>Well, I tried Network Stumbler and it did show similar things to the USR
>site survey tool.

OK, so it's probably a real problem and not the browser cache. So
much for easy solutions and fast fixes.

>Anyway, I did a factory reset on the router and 'upgraded' it with its
>existing firmware, then restored all the settings manually.

Did you reset the router, USING THE WEB INTERFACE, to its default
setting after you "upgraded" the firmware? You cannot assume that
reloading the firmware will also clear the NVRAM area where the
settings are stored. The reset button is suppose to put everything
back to the defaults, but sometimes screws up.

It might also be a problem where one cell (bit) in the NVRAM is
"stuck" and cannot be changed.

>It now seems to be stuck on channel 4 instead, but I can connect again,
>so for now it seems fixed. Not ideal, because there's presumably some
>interference with a local network on channel 7, but never mind.

Well, it might hold together but my guess(tm) is that something else
will screw up. The fact that the channel has changed indicates that
the area of NVRAM might be a failing and that things might get worse.
If it's under warranty, I would attempt to get it exchanged. 3Com
wireless boxes are 1 year:
http://www.3com.com/products/en_US/w...ion/index.html


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558