Comment 21 for bug 984552

Same problem on a Thinkpad T420 with a Ultimate-N 6300 (rev 35) WiFi card since 12.04 .

If the WiFi is reconnected after failing without reloading the driver, the problem happens much faster again as if I unloaded/reloaded the iwlwifi driver by modprobe before reconnecting.

Becauseof this I think it is a driver problem and not a ubuntu problem.

There are no problems reported in the syslog (or kernel log).

lspci details of the WiFi module:
03:00.0 Network controller: Intel Corporation Centrino Ultimate-N 6300 (rev 35)
 Subsystem: Intel Corporation Centrino Ultimate-N 6300 3x3 AGN
 Flags: bus master, fast devsel, latency 0, IRQ 44
 Memory at f2400000 (64-bit, non-prefetchable) [size=8K]
 Capabilities: [c8] Power Management version 3
 Capabilities: [d0] MSI: Enable+ Count=1/1 Maskable- 64bit+
 Capabilities: [e0] Express Endpoint, MSI 00
 Capabilities: [100] Advanced Error Reporting
 Capabilities: [140] Device Serial Number 00-24-d7-ff-ff-e2-d3-c0
 Kernel driver in use: iwlwifi
 Kernel modules: iwlwifi