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Flex6400: remote control across subnet boundaries?

Tor Member ✭✭
Hello to the round,
my name is "Tor", my callsign is DM1TS and I live near Dresden in East Germany. I have recently started using a used Flex6400.

Unfortunately, I live in the valley and the frequency spectrum is completely disturbed by many PLC modems, so the device is to go to a friendly OM in his property. He lives on a mountain and has no interference at all - a dream!

We have been connecting our networks for a few years to be able to access each other's resources together and crosswise. For this purpose, we have built a WLAN with directional antennas for the 6km distance, on which we achieve stable 300MBit/s and ping times of less than 5ms. Both houses have their own LAN and internet access. Each has its own DHCP server and we are therefore completely independent of the other.
The WLAN link between us is built as its own class B subnet. The respective end devices (Ubiquiti PowerStation) are each set up as routers and there is static routing to the opposite side on both sides. We have absolutely no problems with data exchange, everything runs perfectly.

What I can't manage now, however, is the connection from my network via the direct WLAN link to the Flex6400 in its network. It is completely absurd to establish the connection via WAN using Smartlink. My internet line is quite slow and we have a super-fast direct connection.
Unfortunately you can't specify a destination IP address to reach your Flex6400. If that would work, I would be rid of all my worries.

Who has an idea how to configure this situation? I am not aware that UDP works as a basis for UPnP across subnet boundaries. Unfortunately switching to a bridge mode is out of the question as both networks should not lose their independence.

Is there a trick to persuade SSDR to address a specific IP address (that of the Flex6400 in a remote network) via command line parameters?

Here is a small sketch of the situation:


73s, Tor


  • Ted  VE3TRQ
    Ted VE3TRQ Member ✭✭✭

    Just a quick initial comment- why not use a VPN (like SoftEther, which bridges broadcast traffic) set up on two small devices, one in each location, then connect the Flex and SSDR to that device, one each end? There may be easier ways base on IP address values instead of connecting to the two VPN devices, but that would be a quick solution.

    Theother way could be to use the Ubiquiti device Ethernet ports themselves, assuming they are accessible. Not having details prohibits further advice. I am sure others will offer solutions also.

  • Tor
    Tor Member ✭✭
    Hi Ted,
    from my point of view, if I set up a VPN link between the Flex and my house, it is then an exclusive connection just for me. My buddy at the other location would then no longer be able to access the Flex6400 locally, right? I'm also afraid that the smartlink function that I want to set up for two other OMs in another state will no longer work.

    But that's still an interesting approach, thank you very much!

    73s, Tor
    DM1TS, JO61OB
  • John K3MA
    John K3MA Member ✭✭
    edited February 2021

    There maybe other suggestions but here is how we did it at a friends house that had the same topography. The radio station shack was located about 500 ft from the house. The station shack had it's own internet service and LAN. The operating position was located thru the at the residence house. The house had it own internet service and LAN. A microwave link was setup between the house and the station shack.

    We setup a router (maybe bridge mode or access point but I do not remember clearly) at the house connected to the 5GHZ wireless LAN device at the house. We could plug any device (laptop or computer) into one of the LAN ports on the router or connect to the router via wifi. They would pickup a IP address from the router located at the station over the 5GHz link. Then the device running SmartSDR was connected to that network and accessed the Flex radio directly. We did not find a good way to bridge the two different house LAN together such that any computer on any LAN could access the Flex directly. This worked very well but you may have other issues regarding access to the other person network that may or may not be controllable with passwords or other network restrictions. We did not have to worry about those things as both sides of the microwave points were owned by the same person.

    I will state I am not a MS Certified Network tech. This setup was derived by a good working knowledge of networking at the time (5 or more years ago) and trial and error. There may be more elegant solutions now.

    John K3MA

  • WX7Y
    WX7Y Member ✭✭✭✭

    Tor, with SmartEther VPN you set the number of users in the VPN Server I have had 3 connections coming in at the same time and EACH user has there own Login and password so you can keep yours private, The SmartEther VPN will run just fine on a Windows Computer on the Network the Radio is on if you have one or a Raspberry Pi on the same network.

    Of course the more users you have the better the Network and computer needs to be.

  • Tor
    Tor Member ✭✭
    Well I understood it as follows:

    With SoftEtherVPN you can set up a LAN-2-LAN VPN using a virtual L3 switch. This ensures that completely separate networks can communicate with each other down to the L2 level. This in turn is necessary to be able to transport UDP packets from LAN1 to LAN2 (...LANn) and SmartSDR thus finds its way to the Flexradio in a foreign network.
    Such a VPN can be set up with RaspberryPi computers in any participating network. One location is the VPN server and all other locations run in VPN bridge mode.

    I hope I have interpreted this correctly. This would indeed be the solution for my situation. Of course, it would be important that these VPN connections have a kind of keepalive and reconnect themselves.

    Nevertheless, I would find it great if the SmartSDR software would allow the direct entry of a static IP in a future version. As far as I know, this is possible with the client for MAC, at least that's what I read. If this is true, it should also apply to Windows!

    73s, Tor
    DM1TS, JO61OB

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