I posted this on the Archlinux forum. Hoping somebody else will have an idea of what the hell is going on with my wireless:

I've recently purchased a new Lenovo Thinkpad T420s.

I have a Buffalo WHR-HP-G300N running the latest version of DD-WRT.

The wireless router has been working fine for over a year. I've had other laptops attach. The kids ipods, iphones, etc all work great with it.

I can successfully connect to the router without any problems. If I do minimal activities (like ping google.ca) then the router works fine. As soon as I try to visit any web pages the router completely hangs. I actually have to unplug and plug it back in.


Here's the last bunch of lines on /var/log/everything.log

Jun 28 20:22:00 jhlaptop NetworkManager[763]: gateway 172.30.0.1
Jun 28 20:22:00 jhlaptop NetworkManager[763]: nameserver '172.30.0.1'
Jun 28 20:22:00 jhlaptop NetworkManager[763]: domain name 'localdomain'
Jun 28 20:22:00 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 5 of 5 (IP Configure Commit) scheduled...
Jun 28 20:22:00 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 4 of 5 (IP4 Configure Get) complete.
Jun 28 20:22:00 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 5 of 5 (IP Configure Commit) started...
Jun 28 20:22:01 jhlaptop NetworkManager[763]: (wlan0): device state change: ip-config -> activated (reason 'none') [70 100 0]
Jun 28 20:22:01 jhlaptop NetworkManager[763]: Policy set 'mynet 1' (wlan0) as default for IPv4 routing and DNS.
Jun 28 20:22:01 jhlaptop NetworkManager[763]: Activation (wlan0) successful, device activated.
Jun 28 20:22:01 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 5 of 5 (IP Configure Commit) complete.
Jun 28 20:22:01 jhlaptop dbus[738]: [system] Activating service name='org.freedesktop.nm_dispatcher' (using servicehelper)
Jun 28 20:22:01 jhlaptop dbus[738]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
Jun 28 20:22:20 jhlaptop kernel: [ 807.315592] iwlagn 0000:03:00.0: iwlagn_tx_agg_start on ra = 00:23:a4:13:67:44 tid = 0
Jun 28 20:22:26 jhlaptop kernel: [ 813.474483] iwlagn 0000:03:00.0: Stopping AGG while state not ON or starting
Jun 28 20:22:26 jhlaptop kernel: [ 813.547619] cfg80211: Calling CRDA to update world regulatory domain
Jun 28 20:22:26 jhlaptop NetworkManager[763]: (wlan0): supplicant interface state: completed -> disconnected
Jun 28 20:22:26 jhlaptop NetworkManager[763]: (wlan0): supplicant interface state: disconnected -> scanning
Jun 28 20:22:42 jhlaptop NetworkManager[763]: (wlan0): device state change: activated -> disconnected (reason 'supplicant-timeout') [100 30 11]
Jun 28 20:22:42 jhlaptop NetworkManager[763]: (wlan0): deactivating device (reason: 11).
Jun 28 20:22:42 jhlaptop dhcpcd[1670]: received SIGTERM, stopping
Jun 28 20:22:42 jhlaptop dhcpcd[1670]: wlan0: removing interface
Jun 28 20:22:42 jhlaptop NetworkManager[763]: (wlan0): canceled DHCP transaction, DHCP client pid 1670
Jun 28 20:22:42 jhlaptop NetworkManager[763]: (pid 1670) unhandled DHCP event for interface wlan0
Jun 28 20:22:42 jhlaptop dbus[738]: [system] Activating service name='org.freedesktop.nm_dispatcher' (using servicehelper)
Jun 28 20:22:42 jhlaptop NetworkManager[763]: (wlan0): supplicant interface state: scanning -> disconnected
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Couldn't disconnect supplicant interface: This interface is not connected.
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0) starting connection 'mynet 1'
Jun 28 20:22:42 jhlaptop NetworkManager[763]: (wlan0): device state change: disconnected -> prepare (reason 'none') [30 40 0]
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 1 of 5 (Device Prepare) scheduled...
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 1 of 5 (Device Prepare) started...
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 2 of 5 (Device Configure) scheduled...
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 1 of 5 (Device Prepare) complete.
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 2 of 5 (Device Configure) starting...
Jun 28 20:22:42 jhlaptop NetworkManager[763]: (wlan0): device state change: prepare -> config (reason 'none') [40 50 0]
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0/wireless): access point 'mynet 1' has security, but secrets are required.
Jun 28 20:22:42 jhlaptop NetworkManager[763]: (wlan0): device state change: config -> need-auth (reason 'none') [50 60 0]
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 2 of 5 (Device Configure) complete.
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 1 of 5 (Device Prepare) scheduled...
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 1 of 5 (Device Prepare) started...
Jun 28 20:22:42 jhlaptop NetworkManager[763]: (wlan0): device state change: need-auth -> prepare (reason 'none') [60 40 0]
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 2 of 5 (Device Configure) scheduled...
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 1 of 5 (Device Prepare) complete.
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 2 of 5 (Device Configure) starting...
Jun 28 20:22:42 jhlaptop NetworkManager[763]: (wlan0): device state change: prepare -> config (reason 'none') [40 50 0]
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0/wireless): connection 'mynet 1' has security, and secrets exist. No new secrets needed.
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Config: added 'ssid' value 'mynet'
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Config: added 'scan_ssid' value '1'
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Config: added 'key_mgmt' value 'WPA-PSK'
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Config: added 'psk' value ''
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Activation (wlan0) Stage 2 of 5 (Device Configure) complete.
Jun 28 20:22:42 jhlaptop NetworkManager[763]: Config: set interface ap_scan to 1
Jun 28 20:22:42 jhlaptop dbus[738]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
Jun 28 20:22:42 jhlaptop NetworkManager[763]: (wlan0): supplicant interface state: disconnected -> scanning
Jun 28 20:23:06 jhlaptop NetworkManager[763]: (wlan0): device state change: config -> disconnected (reason 'user-requested') [50 30 39]
Jun 28 20:23:06 jhlaptop NetworkManager[763]: (wlan0): deactivating device (reason: 39).
Jun 28 20:23:06 jhlaptop NetworkManager[763]: Couldn't disconnect supplicant interface: This interface is not connected.
Jun 28 20:23:07 jhlaptop NetworkManager[763]: (wlan0): supplicant interface state: scanning -> inactive

Details on hardware:

iwlagn: Intel(R) Wireless WiFi Link AGN driver for Linux, in-tree:
iwlagn: Copyright(c) 2003-2010 Intel Corporation
iwlagn 0000:03:00.0: Detected Intel(R) Centrino(R) Ultimate-N 6300 AGN, REV=0x74

# cat /etc/rc.conf | egrep -v "(^#.*|^$)"

LOCALE="en_US.UTF-8"
DAEMON_LOCALE="no"
HARDWARECLOCK="localtime"
TIMEZONE="America/Vancouver"
KEYMAP="us"
CONSOLEFONT=
CONSOLEMAP=
USECOLOR="yes"
VERBOSE="3"
MODULES=(tp_smapi hdaps)
UDEV_TIMEOUT=30
USEDMRAID="no"
USEBTRFS="no"
USELVM="no"
HOSTNAME="jhlaptop"
NETWORK_PERSIST="no"
DAEMONS=(hwclock syslog-ng dbus networkmanager @alsa acpid netfs crond slim)

# pacman -Ss wireless | grep installed

core/wireless_tools 29-4 [installed]
core/wpa_supplicant 0.7.3-3 (base) [installed]

I found a work around that I don't really like. After fiddling with every F***** setting I could think of, I finally discovered that if I switch the router to G mode only then I can connect without any issues. Is the problem then the Centrino drivers that are being used? is it an issue with my wireless configuration? What else could it be?

I've received a recommendation to try wicd. If I find the time, I'll try that this weekend.