Networking – Two internet connections, two routers, one network

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So here is my situation. We recently got another internet connection setup here at home, which means we have two now. Each internet connection has its own router (both routers have a built in modem, if that matters). Now, on our existing local network, we have a NAS that we use for backups and such.

I am using Windows 7 or 8 on all of our PC's. The router that is used for the first of the internet connections is running DD-WRT. The router that is used for the new internet connection is a ZyXel P-2601HN-F1.

The NAS is just a PC that I built running Windows Server. The new router is not connected to the old one at the moment, so the PC's connected to the old router cannot be accessed if you are connected to the new one. What I am trying to do is to connect the two together, so that I would be able to access the PC's regardless of which router I am connected to.

The problem I am facing now, is that when you are connected to the new internet connection via the new router, you of cause don't have access to the computers and the NAS on the other network since they aren't connected in any way. How would I go about connecting the two networks so that you can access the NAS and computers no matter what router you are connected to? Would it be as simple as disabling DHCP on one of the routers and connecting the other one to it?

Best Answer

Yes, disable DHCP on one of the routers, and give it a static IP address in the range that the other router uses.

Then connect the LAN ports of the two routers together.

This means that you now only have one internal network, and two ways to get to the internet. You can only have one default route, so only one of these routers can be used for "general" traffic at a time. So your options are to

  1. Manually switch the default gateway of some devices to use the other router as default gateway
  2. Set up static routes so some destinations are routed through the other router

Given that you are intending to dedicate one of the DSL lines to the NAS for downloads, this is straightforward. Give the NAS a static IP address, and make its default gateway the router on the dedicated line.

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