[tlug] Setting up a Reliable Local WiFi Network

[CL <az.4tlug@example.com>]

I am having numerous problems trying to set up three Lenovo ThinkPads to 
share a single WiFi connection at home along with two machines connected 
to the Ethernet side of the same router.  The problems only regularly 
occur in our wlan-capable Kubuntu machines.  I have a feeling I am 
forgetting something or configuring something wrong but, after three 
setup run throughs this morning, am still in the dark ... especially 
because the connection "almost always, usually, used to work."  
Discussion of what was happening when it stopped working is below. 

We may have two problems or one big problem; establishing a reliable 
connection among several single-core CPU Ethernet and dual-core WiFi 
machines and bandwidth hogging by one of the dual-core Kubuntu 
machines.  Right now, I do not know which is the correct problem in need 
of solving nor which of the two should be solved first.
THE PCs:  Of the three ThinkPad R61s, one runs WIN XP-J and two are 
running Kubuntu.  The WIN machine was used to install and configure the 
router when it was purchased and connects reliably via eth0 or wlan0.   
This post is being sent from the Ethernet side of the router.  Neither 
of the two Kubuntu machines are able to form a long-term connection and, 
since last evening, KNetworkManager is reporting that wlan0 is 
disconnected.  The R61s use an Intel PRO/Wireless 3945 ABG Network chip. 

ROUTER AND WLAN:  First off, the Net connection is FLETs ADSL 40.  
Hikari cables go right past our second floor window.  NTT East has 
decreed that no one around here really needs hikari until 2012, but 
people down in Kashima, Mito, and central Hokota need it now. 

Router is a Buffalo WHR-G300N.  It was set up for both Ethernet and 
wireless using the boxed CD and my wife's XP-J ThinkPad, which has no 
trouble making a solid 54Mbps wireless connection and also can be 
plugged into the Ethernet side, alternatively.  XP installed some sort 
of driver for the router, which makes me wonder whether I need something 
similar for the Kubuntu machines ... and I cannot find anything that 
says one is necessary.
We've previously been able to run the two Kubuntu ThinkPads off the wlan 
connection by simply letting KNetworkManager find the connection and 
then typing in the Shared Key.  Connections are being auto configured as 
WPA Personal type.  KNetworkManager has found two iterations of the base 
WiFi signal which it designates as (router s/n) and (router s/n-2).  It 
has also identified an AOSS (Buffalo's proprietary protected mode) 
connection, but that disappears and reappears from time to time.  Signal 
strength within both floors of this building ranges from a high of 99% 
to a low of 85% ... and on to zero last evening.
I have two old P4 ThinkCentres and an Aquos television connected to the 
Ethernet side, one runs Xubuntu (my daughter's machine) and the other 
Kubuntu (for torrenting and playback).  The TV is the screen for both 
boxes and I have a CPU switcher between them.  The ThinkCentres were 
added to the eth0 side over the weekend and ran okay with the WIN XP-J 
ThinkPad on the wlan0 side of things.  

WHAT PREDATED THE RECENT PROBLEM:  Our house has a 1DK apartment on the 
second floor and the main purpose of the wlan is to allow the tenant 
Internet access.  Last night , we fired up one of the Kubuntu ThinkPads 
in the apartment, got a solid 54Mbps connection going, and the tenant 
started a torrenting prog running after checking mail.  Net access among 
the other machines, single and dual-core alike, fell to zero.  The 
ThinkCentres, in particular, which had been running fine, suddenly 
developed torrent, updater, and mail login timeouts and failures.  We 
shut down the Kubuntu ThinkPad, and once again had full Net access for 
the WIN ThinkPad and the two Ethernet machines.  However, all attempts 
to reconnect either of the Kubuntu ThinkPads have resulted in 
"disconnect" messages.  We've tried:
1.  Rebooting the PCs.

2.  Rebooting the router.

3.  Rebooting the modem.

4.  Rebooting everything simultaneously.

... with no change.  I am stumped.  Any suggestions what I should do 
next.  There is a pond across the road and the temptation to try my 
overhand programming method is great.  But, I think I should try to 
straighten this out a bit more diligently first.
--
CL