Wlan connection drops frequently. Firmware problem?

[mjokesville]

Greetings all.

I am having wlan connectivity problems with my Intel Centrino Advanced-N 6205. I am using WPA2-PSK, signal strength is good, authorization works fine. But every time I am starting a download the connection drops after a few seconds. Then follows a new eapol handshake, the download proceeds and the connection drops again after 2-5 seconds (Edit: actually up to 20 sec). Another successful handshake and so on...

So far I tried the following:
Reboot the AP: no effect.
Use an external wlan card: works fine.
Use a fake mac and different ip: same problem.

What else can I try to solve this? Might it be a firmware bug?
I am running Fedora 20 with the latest updates.

[lightman47]

For what it's worth - in the past I have had similar problems with Netgear and D-Link wireless routers. It wasn't as short as your 2-5 seconds, but they would keep disconnecting certain devices - I always thought it might have to do with lease renewals. Replacing mine with another brand solved the problem.

[mjokesville]

I forgot to mention: The AP is a Vodafone EasyBox 803, manufactured by Arcadyan.

Here is some additional info:
$ dmesg | grep iwl
[ 14.065118] iwlwifi 0000:03:00.0: can't disable ASPM; OS doesn't have ASPM control
[ 14.065322] iwlwifi 0000:03:00.0: irq 27 for MSI/MSI-X
[ 14.132598] iwlwifi 0000:03:00.0: loaded firmware version 18.168.6.1 op_mode iwldvm
[ 14.186416] iwlwifi 0000:03:00.0: CONFIG_IWLWIFI_DEBUG enabled
[ 14.186422] iwlwifi 0000:03:00.0: CONFIG_IWLWIFI_DEBUGFS enabled
[ 14.186425] iwlwifi 0000:03:00.0: CONFIG_IWLWIFI_DEVICE_TRACING disabled
[ 14.186428] iwlwifi 0000:03:00.0: Detected Intel(R) Centrino(R) Advanced-N 6205 AGN, REV=0xB0
[ 14.186531] iwlwifi 0000:03:00.0: L1 Enabled - LTR Disabled
[ 14.211111] ieee80211 phy0: Selected rate control algorithm 'iwl-agn-rs'
[ 14.378334] iwlwifi 0000:03:00.0 wlp3s0: renamed from wlan0
[ 19.326323] iwlwifi 0000:03:00.0: L1 Enabled - LTR Disabled
[ 19.326555] iwlwifi 0000:03:00.0: Radio type=0x1-0x2-0x0
[ 19.590898] iwlwifi 0000:03:00.0: L1 Enabled - LTR Disabled
[ 19.591117] iwlwifi 0000:03:00.0: Radio type=0x1-0x2-0x0
$ rpm -qa | grep iwl
iwl100-firmware-39.31.5.1-41.fc20.noarch
iwl105-firmware-18.168.6.1-41.fc20.noarch
iwl2030-firmware-18.168.6.1-41.fc20.noarch
iwl2000-firmware-18.168.6.1-41.fc20.noarch
iwl6050-firmware-41.28.5.1-41.fc20.noarch
iwl5150-firmware-8.24.2.2-41.fc20.noarch
iwl3945-firmware-15.32.2.9-41.fc20.noarch
iwl6000g2b-firmware-17.168.5.2-41.fc20.noarch
iwl4965-firmware-228.61.2.24-41.fc20.noarch
iwl1000-firmware-39.31.5.1-41.fc20.noarch
iwl6000g2a-firmware-17.168.5.3-41.fc20.noarch
iwl135-firmware-18.168.6.1-41.fc20.noarch
iwl3160-firmware-25.222.9.0-41.fc20.noarch
iwl5000-firmware-8.83.5.1_1-41.fc20.noarch
iwl6000-firmware-9.221.4.1-41.fc20.noarch
iwl7260-firmware-25.222.9.0-41.fc20.noarch

@lightman
That is why I was trying with a fake mac address. To find out if the AP is treating clients different by vendor. Unfortunately i don't have the opportunity to test with different APs at the moment. I will do that the next days and report.

[mjokesville]

Because lightman47 said he had the same problem with longer intervals, i looked at a bigger sample. Turns out only the minority of reconnects are under 5 seconds, most are between 5 and 10. Sometimes the connection is alive up to 20 sec.

I played with the iwlwifi module options. So far I tried swcrypto=1 and 11n_disable=1 without success.

Here is a snippet from wpa_supplicant.log:
dbus: wpas_dbus_bss_signal_prop_changed: Unknown Property value 7
wlp3s0: SME: Trying to authenticate with 74:31:70:xx:xx:xx (SSID='xxxx' freq=2412 MHz)
wlp3s0: Trying to associate with 74:31:70:xx:xx:xx (SSID='xxxx' freq=2412 MHz)
wlp3s0: Associated with 74:31:70:xx:xx:xx
wlp3s0: WPA: Key negotiation completed with 74:31:70:xx:xx:xx [PTK=CCMP GTK=TKIP]
wlp3s0: CTRL-EVENT-CONNECTED - Connection to 74:31:70:xx:xx:xx completed [id=0 id_str=]
wlp3s0: CTRL-EVENT-DISCONNECTED bssid=74:31:70:xx:xx:xx reason=3
wlp3s0: SME: Trying to authenticate with 74:31:70:xx:xx:xx (SSID='xxxx' freq=2412 MHz)
wlp3s0: Trying to associate with 74:31:70:xx:xx:xx (SSID='xxxx' freq=2412 MHz)
wlp3s0: Associated with 74:31:70:xx:xx:xx
wlp3s0: WPA: Key negotiation completed with 74:31:70:xx:xx:xx [PTK=CCMP GTK=TKIP]
wlp3s0: CTRL-EVENT-CONNECTED - Connection to 74:31:70:xx:xx:xx completed [id=0 id_str=]
wlp3s0: CTRL-EVENT-DISCONNECTED bssid=74:31:70:xx:xx:xx reason=3
wlp3s0: SME: Trying to authenticate with 74:31:70:xx:xx:xx (SSID='xxxx' freq=2412 MHz)
wlp3s0: Trying to associate with 74:31:70:xx:xx:xx (SSID='xxxx' freq=2412 MHz)
wlp3s0: Associated with 74:31:70:xx:xx:xx
wlp3s0: WPA: Key negotiation completed with 74:31:70:xx:xx:xx [PTK=CCMP GTK=TKIP]
wlp3s0: CTRL-EVENT-CONNECTED - Connection to 74:31:70:xx:xx:xx completed [id=0 id_str=]
wlp3s0: CTRL-EVENT-DISCONNECTED bssid=74:31:70:xx:xx:xx reason=3
...

Does anyone know what "reason=3" means?

[kurtdriver]

Reason Codes.

[mjokesville]

That did the trick:
# echo "options iwlwifi 11n_disable=1" >> /etc/modprobe.d/iwlwifi.conf
# reboot

I don't know why it didn't work the first time. Maybe i had a syntax error.