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Can Smartlink work with "Double NAT" on my network?

Neal Pollack, N6YFM
Neal Pollack, N6YFM Member ✭✭
I know this was asked 1 year ago, but not with enough resolution or detail to let me know if I need to rebuild my household network.

I have Verizon (now Frontier) FIOS in the Los Angeles, CA area.   Because the TV set top boxes, DVR, and guide all require that the Verizon NAT router stay in place, I can't change that to bridge mode, but I could add port forward rules if I want.    The LAN subnet for  the Verizon part of our house is 192.168.1.__ as expected.

My shack is in the garage, the other end of the house.   That section of the house is fed with google wifi high speed mesh network points, on LAN subnet 192.168.86.__, with a wire on the Wifi node near my shack coming down to a gigabit switch, which has the radio and my shack PC on it.  This all (google Wifi nodes) represents the second NAT layer.    Running a new LAN cable
all the way back to the Verizon Router "could" be done, but at very great effort/expense (under house, up inside wall, across attic, down inside wall, etc).

QUESTION:   Can Smartlink be made to find the radio if a port forward rule was entered on both the Verizon NAT router, and also on the Google Wifi NAT node for the second LAN?
Or is Flex Smartlink more complicated than that, and simply not going to work with double NAT?
Does anyone have an example of what needs to be configured for which TCP/UDP ports?




  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited June 2018
    If you have configuration control over both routers doing NAT and both routers are capable of doing manual port forwarding, then it is possible.  Usually, you do not have configuration control of the first router doing NAT.

    You essentially set up cascaded port forwarding.  Router 1 forwards 4994/tcp to port 4994/tcp on router 2.  Then router 2 port forwards 4994/tcp to the radio's port 4994/tcp.  Do the same for 4993/udp

  • Ria
    Ria Member ✭✭✭
    edited November 2019
    I've set this up once for someone. He was in an RV park and he knew the owner of the park, so we were able to forward the main router. BUt as Tim said, if you don't have that, no go.
  • K1DBO
    K1DBO Member ✭✭✭
    edited June 2018

    If fios out there is like fios back here (Boston) you might be able to get rid of their router or use it in bridge mode.  At the ONT we have the choice to bring internet in through CAT5 or coax.  They usually set folks for coax because it makes things easy for them.  But if you ask they'll switch you to CAT5 and then you can just plug in your own router.  It's what I do... but only solves half your problem.

    The other way to solve the same half of your problem is to put their "coax router" into bridge mode (as you have already mentioned).  But then your set top boxes wont have the internet they need for program guides, etc.

    So to fix this, they gave me a CAT5 to coax media converter.  It takes your network and puts it back on your coax where your other devices can make use of it.  The device is a few years old now  but Verizon branded with a ECB2200V model number.  Generically, the device is known as a MoCA network adapter and can be found in the usual places.  You might be able to find a tech at Frontier that knows about these devices.  They didnt even charge me for mine.


  • Mike McIntosh
    Mike McIntosh Member ✭✭

    I am having no success with "double nat" routing. I have a Cisco Small Business firewall that connects to a DSL modem. It is configured to route: Always Allow; 4994; Any Source; Destination Same with port 4993. (wan side address) is a NetGear Wifi plus switch router configured to route: External port 4994; Internal Port 4994; Internal IP Address (my Flex 6700).

    This configuration doesn't work. I get a red light on the Maestro test screen even though it recognizes the radio exists. I obviously have something wrong but can't determine what it is. Help will be very much appreciated.

  • Mike McIntosh
    Mike McIntosh Member ✭✭

    Forgot to say I do the same with port 4993 on the NetGear router.

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    HI Mike, I would submit a helpdesk ticket. Flex has long experience with this kind of thing.

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