Setup up multiple routers

How do I go about setting up a new router with one already in place? It's a linksys wrt54gl if anyone has any experience with those. I went to the router's page and tried switching it from a gateway to a router but that did not work. Does anyone know what I'm missing?

bridge the other router

Are you trying to cascade them, use the new router just as a WAP, or something else?

I want to use it as a WAP, but it will have an ethernet line to my  PC.

I want to use it as a FAP, but I didn't find it very hot.

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1.  Connect a PC to one of the LAN ports on the new router.
2.  Turn off DHCP and configure wireless settings in the new router's config screen.
3.  Assign a static IP to the new router (which is now no longer going to be used as a router) for it to use on your existing network, so that you can still log into its config screen at a known address.
4.  Connect the new non-router to your existing network using a LAN port (NOT WAN - don't use it for anything).

You now have a WAP/ethernet switch that isn't trying to assign IP addresses to everything that connects to it (your existing router will take care of that instead).