How does the internet work?

How can I get the Internet to work if I have multiple routers/power line devices?

• When I connect my modem (supplied by the ISP and is capable itself of WiFi and multiple ports) to most of my routers and powerline devices), the internet works fine around my house.  Problems arise when I try to add my Linksys WRT610N router to the network. if a cable from my modem is connected to the WAN (yellow) port of my WRT610N router, the internet everywhere else can work, but my WRT610N doesn't if a cable from my modem is connected to the LAN (blue) port of my WRT610N router, the internet on my WRT610N router usually works, but internet in all my other devices gets messed-up.  I am unable to receive internet on powerline devices and the other routers directly connected to my modem. In advanced routing mode, I noticed that NAT mode is disabled and Dynamic routing (RIP) is also disabled.  My internet is DHCP type.  Isn't there any IP conflicts likely?

• Answer:

  Home routers are meant to deal with one and only one situation: a single uplink to your ISP and then wired and WiFi access downstream.  If you hook up the routers in series, as you're doing in the first situation, you will confuse things, as you've seen.  Straightening that out would definitely require working with the system directly. Your second situation is even worse and you're bypassing the firewall and NAT functionality of the router.  I don't think you meant to do that. Why not just make use of the first router?