Final answer:
To connect five computers to a router with four ports, the least expensive solution is to use a network switch. This device will expand the single router port, allowing all five computers to be connected through wired connections.
Step-by-step explanation:
The least expensive way to connect five computers using a wired network to a router that has only four network ports is to use a network switch. A network switch is a networking device that allows you to connect multiple devices to a single router by providing additional network ports.
To do this, you would connect the network switch to one of the ports on the router using a standard Ethernet cable. Then, you would connect each of the five computers to the switch. This way, four computers would be connected directly to the switch, and the fifth would effectively share the router's port that the switch is connected to.
The cost of a basic network switch is generally lower than purchasing a new router with more ports or setting up a wireless network, making it the most cost-effective solution for this situation.