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Wynn16's avatar
Wynn16
Aspirant
Jan 31, 2016

Connecting R7000 with Xfinity gateway in bridge mode - use WAN or LAN?

This seems to be a common problem but I still can't get the answer.  I have an Xfinity XB3 wireless gateway (Cisco model #DPC3941T) and a Netgear R7000 Nighthawk wireless router.  I've set the Xfinity XB3 into bridge mode so I can use the R7000 as my wireless router instead.  I have 2 questions:

 

1) In the above scenario, I can only get the R7000 to connect to the Internet if I use the WAN port (connected to port1 on the XB3).  If I try to connect the Xfinity XB3 wireless gateway (in bridge mode) to the LAN port of my R7000, I cannot connect to the Internet.  Furthermore, even when I am connected to the Internet using the WAN port, other devices connected to the any of the four LAN ports do not get Internet connection.  Does this make sense?  Are the WAN and LAN networks totally separate?  Is there a way I can keep the above scenario using my R7000 as my wireless router and also use the LAN ports?

 

2) What is the difference between the setup I have described above versus using the Xfinity XB3 wireless gateway as my wireless router and setting my R7000 as a wireless access point?  Is one method better than the other (I'm assuming the Netgear R7000 is a better/more secure wireless router than the Xfinity XB3 wireless gateway)?  Wirelss coverage is not a big problem and I currently have both products together in 1 room.  

 

Thanks in advance for any responses.

Troubleshooting

9 Replies

  • TheEther's avatar
    TheEther
    Guru
    Feb 01, 2016
    1. The WAN and LAN networks are separate.  When functioning as a router, the R7000 is also a firewall that protects your LAN network from intruders.  

      You should make sure that the LAN and WAN networks are in different subnets.  The Xfinity is probably using 192.168.1.0/255.255.255.0, so change your LAN to something different.  10.0.0.0/255.255.255.0 or 192.168.2.0/255.255.255.0 should work.  Once you change the subnet, your devices will have to renew their DHCP leases in order to pick up IP addresses in the new subnet.  Then, retest Internet connectivity.

    2. Mainly, it is a choice between using the routing/firewall functions in your R7000 versus your Xfinity gateway.  They probably have different capabilities and performance, so you will have to decide what's important to you.  

      But there are secondary considerations.  If you have IPTV settop boxes, then you may or may not have difficulty running them behind the R7000.  IPTV depends on IP Multicast, which Netgear occasionally has difficulty handling.  You will need to enable IGMP Proxy.  

      Also, Comcast almost certainly has admin access to their gateway, so operating your R7000 as a router gives you the peace of mind that your LAN is entirely isolated.
  • Wynn16's avatar
    Wynn16
    Aspirant
    Feb 01, 2016
    Thanks TheEther. So I believe that Xfinity local IP network is using 10.0.0.1/255.255.255.0. I'm not sure where to change the subnet for the R7000. I do see a setting that says to get the Internet IP address dynamically from the ISP. Do I need to change it to use a static IP address?
    • TheEther's avatar
      TheEther
      Guru
      Feb 01, 2016

      No, leave the setting to get the Internet IP address dynamically from the ISP.  You should confirm that the IP address listed on that page is a public IP address.  In other words, it should NOT be 192.168.1.X, 10.X.X.X, or 172.16.X.X.  If it IS one those addresses, then the Xfinity gateway is not in bridge mode.  Otherwise, the R7000 should have received a public IP address.

       

      The subnet that you want to change is under ADVANCED > Setup > LAN Setup.  Since the Xfinity gateway is using 10.0.0.1/255.255.255.0, you can change the R7000's LAN IP address to 192.168.1.1 and subnet mask to 255.255.255.0.

       

      • Wynn16's avatar
        Wynn16
        Aspirant
        Feb 01, 2016

        Hmm, so I did what you said and the R7000 LAN port already has the IP address and subnet mask that you suggested.  Which got me to thinking that maybe it's not the router or gateway that's messed up, but rather it's me.  Full disclosure -- what I left out was that I am trying to connect a Netgear Powerline adaptor to the LAN port of the router, which is used to allow web control for my home alarm system.  So I tried to connect my laptop to the LAN port of my R7000 router, and...lo and behold it connects to the Internet fine.

         

        So now my question becomes why does the Powerline adaptor not work when connected to the LAN port of the router (the led light for the LAN port is a solid orange for the Powerline adaptor as opposed to solid white).  It worked fine before I got the Xfinity wireless gateway when I was using my R7000 router with a regular cable modem.  I know less about powerline adaptors than about routers and modems (which is not a lot to begin with) so I'm just throwing this out there without much hope of an answer - maybe I need to go to a different forum?

         

        TheEther - thanks for your help anyways.