Intel Wireless-N 7265

Setup

If you buy a Thinkpad L450 with Intel Wireless-N 7265, you may have some trouble making it run under GNU/Linux:

This card is only supported by Linux kernel 3.13 or higher. When using Debian, this means you need at least Debian/Jessie.
You need a proprietary firmware. On Debian, you need the following package from the non-free section:
```
apt-get install firmware-iwlwifi
```
In a default setup as of 2015-02-23, you will experience a series of fast disconnects and reconnects, making the network almost unusable. Luckily, you can solve this issue by disabling some features of the card.

The following worked for me on Debian/Jessie with Linux kernel 3.16:
```
echo 'options iwlmvm power_scheme=1' >/etc/modprobe.d/iwlmvm.conf
echo 'options iwlwifi bt_coex_active=N 11n_disable=1 swcrypto=1' >/etc/modprobe.d/iwlwifi.conf
```
After making these settings, either reload the kernel modules, or simply reboot.

Replace Firmware

If the above commands don't solve the issue for you, there is a linux-firmware bug tracker entry which provides a newer firmware for testing.

Error messages

For reference, here are the log messages of a dysfunctional setup. The following messages are repeated over and over in dmesg (and thus /var/log/kern.log):

cfg80211: Calling CRDA to update world regulatory domain
cfg80211: World regulatory domain updated:
cfg80211: [...]
wlan0: authenticate with **:**:**:**:**:**
wlan0: send auth to **:**:**:**:**:** (try 1/3)
wlan0: authenticated
wlan0: associate with **:**:**:**:**:** (try 1/3)
wlan0: RX AssocResp from **:**:**:**:**:** (capab=0x411 status=0 aid=1)
wlan0: associated

Additionally, the following messages are repeated in /var/log/daemon.log:

wpa_supplicant[***]: wlan0: CTRL-EVENT-DISCONNECTED bssid=**:**:**:**:**:** reason=4 locally_generated=1
NetworkManager[***]: <warn> Connection disconnected (reason -4)
wpa_supplicant[***]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=CORE type=WORLD
wpa_supplicant[***]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=USER type=COUNTRY alpha2=DE
NetworkManager[***]: <info> (wlan0): supplicant interface state: completed -> disconnected
NetworkManager[***]: <info> (wlan0): supplicant interface state: disconnected -> scanning
wpa_supplicant[***]: wlan0: SME: Trying to authenticate with **:**:**:**:**:** (SSID='***' freq=2412 MHz)
NetworkManager[***]: <info> (wlan0): supplicant interface state: scanning -> authenticating
wpa_supplicant[***]: wlan0: Trying to associate with **:**:**:**:**:** (SSID='***' freq=2412 MHz)
NetworkManager[***]: <info> (wlan0): supplicant interface state: authenticating -> associating
wpa_supplicant[***]: wlan0: Associated with **:**:**:**:**:**
NetworkManager[***]: <info> (wlan0): supplicant interface state: associating -> 4-way handshake
wpa_supplicant[***]: wlan0: WPA: Key negotiation completed with **:**:**:**:**:** [PTK=CCMP GTK=CCMP]
wpa_supplicant[***]: wlan0: CTRL-EVENT-CONNECTED - Connection to **:**:**:**:**:** completed [id=0 id_str=]
NetworkManager[***]: <info> (wlan0): supplicant interface state: 4-way handshake -> completed