Create a connection with a fixed IP address
Most networks will automatically assign anand other details to your computer when you connect to the network. These details can change periodically, but you might want to have a fixed IP address for the computer so you always know what its address is (for example, if it is a file server).
To give your computer a fixed (static) IP address:
Open the Activities overview and start typing Network.
Click on Network to open the panel.
Find the network connection that you want to have a fixed address. Click the button next to the network connection. For a Wi-Fi connection, the button will be located next to the active network.
Select the IPv4 or IPv6 tab and change the Method to Manual.
Type in the IP Address and Gateway, as well as the appropriate Netmask.
In the DNS section, switch the Automatic switch to off. Enter the IP address of a DNS server you want to use. Enter additional DNS server addresses using the + button.
In the Routes section, switch the Automatic switch to off. Enter the Address, Netmask, Gateway and Metric for a route you want to use. Enter additional routes using the + button.
Click Apply. The network connection should now have a fixed IP address.