Business router adding 2nd router


Basically I have a business line from Optimum with 5 statics. They provide a CISCO DPQ 3925 which is locked down like fort knox. But they do mention being able to add a 2nd router behind it for a private LAN to work off of each individual port/static IP.

I've setup and config'd basic routers for dynamic IPs and made private LANs, but never something of this fashion and can't seem to google the right thing for some basic instructions. I currently have a 2nd router running DD-WRT and need some basic advise.

I have the static IP/Mask/Gateway/DNS provided by Optimum and a 2nd router sitting here doing nothing. Any config advise would be appreciated! I used to have a server setup on my local LAN handling DHCP/DNS but for this I would be happy just getting the connection up and running and not having that server setup now.

Edit: Already learned the business modem/router is (even though its bringing in a static IP to each of the 4 ports)

Thanks in advance!
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  1. Please let me know what info is needed to figure out my dilemma. I know it can be done, I'm just not at that level yet and am getting a bit confused. :)

    *If anything I'm an expert at following directions. :P
  2. I'm still trying to get my head around how they've pre-configured this modem/router.

    I assume the 5 static IPs are public, not private, right?

    If you connect a device to one of the LAN ports, do you get a private IP address (e.g.,
  3. Yes, the top 2 lines are correct. However, I would have to match the IP, Mask, Gateway, and DNS to the info they provided when I connected a device. I was however through some stepping back and thinking logically able to figure it out:

    - I plugged port 1 with said public IP address into the WAN on the 2nd router.
    - Setup WAN connection type for "Static IP" and added the matching WAN IP, Mask, Gateway, and ISP DNS.

    I then gave it a lucky guess and set the Router IP to the same standard way I setup any other on a residential connection (and disabled DHCP on 2nd router):


    Then connected business router to the WAN port and a laptop to test to one of the 4 ports on the 2nd router. IT WORKED. I just have so much reading to do now to understand what I was doing. :P

    Sorry for jumping the gun, but in case I didn't figure it out I guessed TH's would be the place to look for help. Now I just have to figure out the rest of my projects/tasks...but at least #1 was done (setting up private LAN for 1 IP address to have multiple devices/servers working off of the 1 IP)

    Now to study my networking. Thanks again for the quick response, and feel free to elaborate on what I did as I just did some logical guess work as I stated. :)

    Just learning the ropes of networking and some basic administration to "move up" in work. This particular network will host a few tiny projects like a private XMPP chat server and maybe a private ventrilo server to start. :D
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