If you have several wired and/or wireless interfaces, the default Ubuntu network-manager program will manage them all. To make the network manager ignore an interface, you must edit the /etc/network/interfaces file.
/etc/network/interfaces file contains network interface configuration information for the both Ubuntu and Debian Linux. This is where you configure how your system is connected to the network.
Look at your current interfaces:
To make network-manager ignore wlan0:
$ sudo nano /etc/network/interfaces
And add the line:
iface wlan0 inet manual
The manual keyword denotes that network-manager should ignore the interface. After a reboot, the network manager will show device not managed for wlan0.…