wireless - Wi-Fi connection fail after configuring wlan - Ask Ubuntu

i have been trying configure wifi connection dns values correct according isp had provided. used network configuration gui ubuntu 14.04 panel , connection works perfectly:

it might of importance publish ifconfig's output when wi-fi connection alive , working:

wlan0     link encap:ethernet  hwaddr 70:1a:04:a4:f0:31             inet addr:192.168.1.104  bcast:192.168.1.255  mask:255.255.255.0           inet6 addr: fe80::721a:4ff:fea4:f031/64 scope:link           broadcast running multicast  mtu:1500  metric:1           rx packets:4658 errors:0 dropped:0 overruns:0 frame:0           tx packets:5685 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:1000            rx bytes:1534231 (1.5 mb)  tx bytes:1228569 (1.2 mb) 

my problem occurred when out of curiosity, tried set values provided isp editing /etc/network/interfaces. deleted numbers dialog box shown above , put below information in interfaces file:

auto wlan0   iface wlan0 inet static   address 192.168.1.120   netmask 255.255.255.0   broadcast 192.168.1.1   dns-nameservers 185.98.113.113 185.98.114.114 

unfortunately after running sudo service network-manager restart in terminal, saw wi-fi connection has dropped , there no networks available anymore.

please me understand has been incorrect in either process i've taken or data have entered interfaces file ?

first of all, interfaces file needs gateway address; not broadcast. second, every wireless interface needs directed connect specific ssid , provide password. suggest amend file to:

auto wlan0   iface wlan0 inet static   address 192.168.1.120   netmask 255.255.255.0   gateway 192.168.1.1   dns-nameservers 185.98.113.113 185.98.114.114   wpa-ssid <your_network>   wpa-psk <your_secret_key> 

finally, network manager needs directed not manage interfaces declared in /etc/network/interfaces. please do:

gksudo gedit /etc/networkmanager/networkmanager.conf 

use nano or kate or leafpad if don't have text editor gedit. make managed=false. if is, close text editor. if not, change it, proofread carefully, save , close text editor.

reboot , check:

ifconfig ping -c3 www.ubuntu.com