D-Link DIR 605L Router set up problem

I have about 100 systems in a network. I have a static IP for Internet, 20.24.0.20 that I put in the Router and set it up as a DHCP server. By default it takes the IP 192.168.0.1. The problem is whenever I start a system before starting the router the system acquires a IP in the series 192.168.1.1, as a result those system could not automatically able to connect to the Internet until I repair the network of that system or restart the system. Why this is happening and What is the remedy?