===== Static IP Address =====
Find your gateway:
  $ netstat -r -n
Find you IP address:
  $ ip addr
For giving the Raspberry Pi a static IP address. Open the interfaces file:
  $ sudo nano /etc/network/interfaces
And change the file to:

   # interfaces(5) file used by ifup(8) and ifdown(8)
   
   # Please note that this file is written to be used with dhcpcd
   # For static IP, consult /etc/dhcpcd.conf and 'man dhcpcd.conf'
   
   # Include files from /etc/network/interfaces.d:
   source-directory /etc/network/interfaces.d
   
   auto lo
   iface lo inet loopback
   
   # Ethernet
    auto eth0
    allow-hotplug eth0
    iface eth0 inet static
     address ???.???.???.???
     netmask 255.255.255.0
     gateway 194.95.203.1
   
   allow-hotplug wlan0
   iface wlan0 inet manual
    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
   
   allow-hotplug wlan1
   iface wlan1 inet manual
    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

Disable the DHCP-Client:   
  $ sudo service dhcpcd stop
  $ sudo systemctl disable dhcpcd 
  
Reboot:\\
  $ sudo reboot