Poor quality of wireless connection

[José Romildo Malaquias]

Hello.

I have a notebook with an Intel Centrino Advanced-N 6230 wireless
card.

In gentoo (kernel 3.4.3-gentoo) and also in Fedora 17 the connection
through it is of poor quality. ping to the router is getting about 50%
packet loss.

With Ubuntu 12.04 and Windows 7 the connection is ok, without packet
loss.

Gentoo, Fedora and Ubuntu are all using the iwlwifi module for the
centrino wireless card.

# lspci -nnv
[...]
08:00.0 Network controller [0280]: Intel Corporation Centrino Advanced-N 6230 [8086:0091] (rev 34)
       Subsystem: Intel Corporation Centrino Advanced-N 6230 AGN [8086:5201]
       Flags: bus master, fast devsel, latency 0, IRQ 18
       Memory at f2d00000 (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 88-53-2e-ff-ff-4f-03-76
       Kernel driver in use: iwlwifi
       Kernel modules: iwlwifi
[...]

Any clues?