[ltp] strange behaviour of wireless

[Richard Neill]

On 09/08/11 17:59, Arno Trautmann wrote:
> Richard Neill wrote:
>>>>
>
>> If Network manager is NOT running, you might try using it: the latest
>> version isn't bad (start the gnome "nm-applet" for a gui, and read logs
>> which are sent to syslog).
>
> zsh: command not found: nm-applet
> (using fluxbox)

The Ubuntu Live CD has network manager installed - sometimes NM seems to 
get the right "magic" to happen (in a, sadly not very well documented 
way); sometimes it seems to (equally silently) get it badly wrong!

>> Try using: http://unetbootin.sourceforge.net/

Also download the latest Ubuntu disk (i.e. Natty, not Lucid) to get the 
latest kernel etc - your choice of Kubuntu/Ubuntu/Xubuntu.


>>
>> I'm beginning to be suspicious of your access point, rather than the
>> Linux side. Is it possible that you are causing it to crash?
>
> Then I wouldn't have access, too, would I?

Well, maybe that explains why you get access just once.

>
>> Or perhaps
>> you are using wireless "a" which is causing the AP to switch away from
>> support for wireless "b" devices, thereby cutting off your roomates?
>
> Maybe? … I'll try to check what my roommates see if they are connected.
> But that seems like a reasonable explanation.
>
>> [Is anyone using equipment older than ~ 4 years?]
>
> The machines should all be around that old, maybe 5 years.
>
>> Does the AP have any form of logging or web control panel? Is it a
>> reasonably recent (this year) model, or a much older one? Is it a
>> "cheap" AP or not?
>> [I hesitate slightly here: some £15 APs are actually much better than
>> some £50 APs: so cheap refers to quality not to price!]
>
> I'll check the model and write you what it is.

I'm wondering whether the AP is doing something awkward. Wireless 
current and legacy devices don't always interact very nicely. If you 
force the AP to a standard setting (perhaps mode g, disable mode a/b/n, 
and set it to WEP), you should get something repeatable, if not optimal.
Then try for WPA2 and n mode only.

BTW, the ranges of n and b/g differ: it could be that as soon as an n 
client connects, your roommates become out of range....

>
> The connection is ok and mostly reliable, but recently I have problems
> with the vpn that is used. vpnc throws something like
> “either "to" is duplicate or "ipid" is a garbage”
> I then have to reboot or wait about 30min until I can connect again. But
> the behaviour changes daily, sometimes I lose the signal after a few
> seconds, while mostly I can stay for hours. But that may rather be an
> access point problem.

I think we should leave troubleshooting the VPN till after you get a 
straightforward connection to work :-)