There are different ways to based on what you are trying to achieve. I played with two routers a few years ago using different brands of routers (a Lynksys "g" and Netgear "n" router). I do not recall the settings I used. First I backed up my router I was using just in case. I placed both routers side by side. Got the first working working with a cable connected PC and WIFI off, then connected the second router to the first, connected a laptop via cable to the second so I could make router changes, and used an iPad to test the WIFI. Got it working but the lack of gigabit speed on the ethernet was limiting. I was trying to not only extend WIFI but also have more LAN ports (for a printer on each router) using the equipment I had at hand. My current setup is just one Archer C8 router. Look at https://www.wikihow.com/Connect-Two-Routers