Hi I have a Asus AC66U in room 2 and I want to extend it's range in living room. Is it possible to use an old Linksys WRT54G to do so? How do I do it? Would using a slower router mean that the wifi in the living room becomes slower?
You can only plug one router into a modem (unless you're a business paying for multiple static IP addresses). Read this sticky on converting a router into a wireless access point. That will do what you want.