My server PC has two network cards:

the first one is used to connect cable modem (internet)
the second one is wireless network. This is connection for laptop.

Laptop is 5m from server.

I want to add the third PC (15m from server) and want to use patch cable. Problem is when i try to assign IP addresses 192.168.0.1 to server, error message pops-up warning me that two same addresses are on same PC. Which one card should have 192.168.0.1