after upgrading ubuntu the network manager still connects to wlan, but internet doesn't work and I can't ping/ reach the wlan router's homepage.

lshw -C network and iwconfig give the following output:

martin@martef:~$ sudo lshw -C network
[sudo] password for martin:
description: Ethernet interface
product: 82566MM Gigabit Network Connection
vendor: Intel Corporation
physical id: 19
bus info: pci@0000:00:19.0
logical name: eth0
version: 03
serial: 00:21:86:52:2c:8c
capacity: 1Gbit/s
width: 32 bits
clock: 33MHz
capabilities: pm msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=1.5.1-k firmware=0.3-0 latency=0 link=no multicast=yes port=twisted pair
resources: irq:47 memory:fe200000-fe21ffff memory:fe225000-fe225fff ioport:1840(size=32)
description: Wireless interface
product: PRO/Wireless 4965 AG or AGN [Kedron] Network Connection
vendor: Intel Corporation
physical id: 0
bus info: pci@0000:03:00.0
logical name: wlan0
version: 61
serial: 00:1f:3b:ad:7d:69
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
configuration: broadcast=yes driver=iwl4965 driverversion=3.2.0-31-generic firmware= ip= latency=0 link=yes multicast=yes wireless=IEEE 802.11abgn
resources: irq:48 memory:df2fe000-df2fffff
martin@martef:~$ iwconfig
lo no wireless extensions.

wlan0 IEEE 802.11abgn ESSID:"mainstation"
Mode:Managed Frequency:2.412 GHz Access Point: 00:13:49:E0:1BE
Bit Rate=1 Mb/s Tx-Power=15 dBm
Retry long limit:7 RTS thrff Fragment thrff
Power Managementff
Link Quality=69/70 Signal level=-41 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:23 Missed beacon:0

eth0 no wireless extensions.

Thanks for helping!