Go to Phone Settings
Select your connection type Wi-Fi
select the blue (>) after name of the wi-fi network
select Static
Now set
IP Address usually something like 192.168.0.10
Subnet Mask 255.255.255.0
Router
DNS
when you connect to the network the address is set
If you have a computer already connected to the network use this to find out the IP Address and other settings to use by doing the first section of this page CLICK HERE
Add one to the last number of the computer IP Address for your new device
e.g. if the computer has an address 192.168.0.10 then use 192.168.0.11