The Router can have its DHCP On or Off. When it is On you can decide on the range of the IP numbers that it would deliver. As an Example: 192.168.1.1 to 192.168.1.20 or 192.168.100.100 to 192.168.100.200
If you want to assign a manual IP to your computers it is done in the computer?s Network setting not by Router.
You can leave the DHCP On, and assign a manual IP in any of your computers provided that the IP number is not within the range of the Router?s DHCP.
Log to this page it has a lot of links to instructions to Windows Network Settings, and Sharing.
Link to:
Windows Network - Installing & Sharing.
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