Wireless under Ubuntu Server 16.04

Install wpasupplicant if not already installed:

sudo apt install wpasupplicant

Find out your Wireless interface name using "iwconfig" command. If it is not installed, install it using

sudo apt install wireless-tools

The interface name will be like wlp3s0 or wlp3s0b1 or something similar to this.

Find the interface name

iwconfig

Add the Wireless interface configuration to /etc/network/interfaces. For example, taking wlp3s0b1 as Wireless interface name:

# wifi interface
auto wlp3s0b1
iface wlp3s0b1 inet dhcp
       wpa-ssid <YOUR WIFI NETWORK NAME>
       wpa-psk <YOUR WIFI NETWORK PASSWORD>

# usb tethering to phone
auto wlp3s0b2
iface wlp3s0b2 inet dhcp

Save /etc/network/interfaces and run

sudo service networking restart

For more detailed instructions, see https://wiki.debian.org/WiFi/HowToUse