If you already have a wireless Broadband router that you'd like to use only as an Access Point and a secondary switch with a separate router for sharing the Internet connection, the process is outlined below:
1. Change the IP of the wireless router to be in the same subnet as the main router without coinciding with the main router's base IP (you might have to plug in the wireless router into a PC to do that). Also disable the wireless router's DHCP server, so it wont conflict with the main router.
Example:
main router IP - 192.168.1.1 base IP, DHCP server range 192.168.1.100 to 192.168.1.200
wireless AP IP - 192.168.1.201 to 253 base IP, DHCP disabled.
2. Connect the Wireless router to the main one using
LAN ports on both routers and a crossoer cable (or uplink port on one of the routers and a straight-through patch cable). Do not use the WAN port on the wireless router to connect to the LAN !
Notes:
Wireless routers can often only be used as an AP in Gateway mode (as opposed to repeater or bridge mode).
All LAN clients should get their internal IPs from one router only.
The WAN port on the wireless router should not be connected to anything.
You might want to turn off NAT on the wireless router.
A more detailed guide is available here:
How to set a Wireless Router as an Access Point
