Static IP

systemctl stop NetworkManager.service

/etc/network/interfaces

 source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet static
      address 10.1.1.125
      netmask 255.0.0.0
      gateway 10.1.1.1

service networking restart