LAN connection doesn't work in some laptops

Hi. My room mates and i recently got an internet connection. Unfortunately, we only have one LAN cable so we need to take turn in using it. It works fine on my netbook but not to them. Windows troubleshoot it and says "Local Area Connection doesn't have a valid IP configuration". What should we do? P.S. At first, i also can't connect via LAN but i windows troubleshoot it, says DHCP was...