In a variation on wireless networking, you can use the wireless router to provide Internet access and file & printer sharing between wireless computers, while isolating the wireless network from the wired network
By changing the order in which the wireless router and the wired router are connected, a wireless router can be used to segregate wireless computers from wired computers in your network. In this manner, you can prevent file and printer sharing and any other type of direct contact between the wired and wireless computers.
You might want to do this for security reasons. For example, if you normally connect a laptop computer using an Ethernet cable, you could set segregate the networks in case someone manages to gain unauthorized access to your wireless network.
The first part of trick to segregating the networks is to connect the WAN (Wide Area Network) port on the wireless router to a LAN (Local Area Network) port on the Cable/DSL modem. That’s the same connection you’d make with a wired router, if you were only using it or were wanting to protect the wireless computers from the wired computers.
This connection will cause the Wireless router to get its IP address assigned by the upstream network’s DHCP server (typically, a cable Internet Sevice Provider or a DSL provider).
The DHCP server within the wireless router should be ON for this setp, as we’ll use it to assign IP addresses to the wireless computers and to the wired Cable/DSL router.
Then, connect the WAN port on the Cable/DSL router to a LAN port on the wireless router. This will make the Cable/DSL router get its "upstream" (WAN) IP address from the wireless router.
The DHCP server within the wired Cable/DSL router should also be turned ON. It should also be set to a different IP address range than that being used by the Wireless router. Linksys normally has these set differently by default: the wireless router uses 192.168.1.x/255.255.255.0, while the wired router uses 192.168.0.x/255.255.255.0.
The bottom line of this configuration is that the wireless computers will be unable to route any connection attempts past the WAN port on the wired router. The wired computers should not be able, but may be able, to initiate connections to (and get responses from) the wireless computers.
Routers should not send outbound any requests that are attempting to contact one of the IP address ranges that are reserved for private networks (e.g., 192.168.x.y/255.255.0.0); however, manufacturers of consumer-grade home routers may not implement that block.