Wireless Disconnects Intermittently with Intel Corporation Centrino Advanced-N 6205 [Taylor Peak] [8086:0085] (rev 34)

I am on Ubuntu 15.04 using xfce (xubuntu) and am having trouble with my wi-fi. The indicator continues to show that I am connected to the network but after some amount of time I will no longer have internet access. In order to fix the issue I simply disconnect from the network and reconnect which always resolves it. I have had this issue occur on different networks.

03:00.0 Network controller [0280]: Intel Corporation Centrino Advanced-N 6205 [Taylor Peak] [8086:0085] (rev 34)
    Subsystem: Intel Corporation Centrino Advanced-N 6205 AGN [8086:1311]
    Kernel driver in use: iwlwifi

Run in terminal

sudo tee /etc/modprobe.d/iwlwifi-opt.conf <<< "options iwlwifi 11n_disable=1 swcrypto=1 bt_coex_active=0 power_save=0"

and reboot.

In many cases only 11n_disable=8 is sufficient.

Explanation:

The iwlwifi Linux kernel driver supports several Intel wireless LAN adapters. The command adds the following configuration to the iwlwifi module:

11n_disable=1      Disables the 802.11n mode
11n_disable=8      Enables agg TX option
swcrypto=1         Disables hardware encryption and uses software instead.
bt_coex_active=0   Disables bluetooth coexistence technology that works poorly with iwlwifi
power_save=0       Disables the power save mode

To restart the services without rebooting to test alternative configurations:

sudo modprobe -r iwldvm iwlwifi
sudo modprobe iwldvm iwlwifi
sudo service network-manager restart

The shorthand command additionally uses a here string via the <<< operator in Bash to append these characters to the configuration file.

In my case, it was a router issue. Despite the fixes suggested above, it turns out that my 6205 adapter could not handle an access point that allowed dynamic steering between 2.4/5 Ghz (called SmartSteering - specific to my router). There are to viable options to help the 6205 adapter:

Connection settings (best - stable now for more than 6 months)

Use a GUI to change the settings for the AP, like nm-connection-editor. The relevant setting would be changing the Band from automatic to a specific Band.

XOR

Router settings (not ideal, but works as well)

I turned off Smart-Steering, allowing the router to broadcast two separate APs, one for 5GHz, another for 2.4GHz (I needed both). Now, I could connect to the 5GHz AP with my laptop with no issues.