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Is it possible to configure SmartLink to cope with double NAT?

m5kvk Member ✭✭

My remote QTH is self-contained with its own firewall/router. It is then connected to the WiFi of the farmer who lets me rent a bit of space, and from there it is connected to the Internet. My router (Teltonika RUT-951) also has a 4G modem as a fallback.

This means two NAT'ing firewalls to transit - mine and the farm's. I have total control over mine, but I have none over the farm's. I don't even know what or where it is (and neither does the farmer).

Currently, I access the remote site over a Zerotier VPN. My home LAN is part of the Zerotier VPN and it is my home router that provides inbound Internet (and Smartlink) access. Unfortunately, the latency is high (only C according to bufferbloat). This is because the farm router doesn't support uPNP, and thus the Zerotier VPN has to use Zerotier's root servers rather going peer-to-peer. I'd like to improve matters.

I can't do anything about the WiFi connection or the farm's router, but is there any way to configure the elements under my control so that I could use Smartlink to access the radio via and farm's IP address, rather than via Zerotier?


  • Ha Gei
    Ha Gei Member ✭✭✭


    The ONLY VPN that will work, is SOFTETHERNET , there is another commercial one , but very expensive :

    YOU NEED OSI Layer and MS-NETBEUI for smarsdr to work.

    But, honestly, with as you will also need to go thru their azure servers..you are more or less lost...high latency is very surely your culprint.


  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin

    Yes, you can do a double NAT, but you need access to the farm you are 'borrowing' it from.

    But, you have to first manually forward the WAN (outside) ports to the IP address of the 2nd Inside router.

    Then, you forward those 2 ports to the IP address of the radio.

    That is assuming your ISP is not running CGNAT which fails in all cases, single or double NAT'd.


  • m5kvk
    m5kvk Member ✭✭

    Thanks, Mike.

    unfortunately, there’s little chance of being able to access the farm router. Like I said, the farmer has no idea where it is! Her grandson fitted it a while back. He now lives in Brazil somewhere :-)

  • David Decoons, wo2x
    David Decoons, wo2x Member, Super Elmer Moderator

    Depending on the router the farmer uses, it may well still have the default password. You can connect your computer direct to the network coming from the farmer, reboot the computer, and in the web browser, enter the gateway address that is assigned. In the Windows world, you can open a command prompt and type ipconfig to see the IP assigned to you and gateway.

    One last thing to try, if their router supports universal Plug and Play, you could put your router into bridge mode and reboot radio and test. NOTE - doing this will expose your devices to be visible from the farmer’s network.

    73 Dave wo2x

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