Edit /etc/rc.local and add below line above exit 0
# vi /etc/rc.local
...
nmcli con up id SSID
exit 0
#
OR
Remove Gnome Network Manager by typing in
#apt-get remove --purge network-manager
Edit /etc/network/interfaces file to look like the following
(SSID and WEP key set accordingly):
# vi /etc/network/interfaces
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet dhcp
auto wlan0
iface wlan0 inet static
address 100.0.0.15
netmask 255.255.255.0
gateway 100.0.0.1
wireless-essid MYSSID
wireless-key 12345678912345678912345678
#