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Flex 6400 Link-Local and Software VPN

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DSherfey
DSherfey Member ✭✭
edited November 2025 in Networking
I have a 6400 and typically run Surfshark as my VPN for traffic on all my computers. I have the 6400 wired directly into my desktop as it is too far from the router to network it that way. Given that there is no plan for remote operation. When I have my VPN turned on SmartSDR, DAX, and CAT can't see the radio. I have all three services set to bypass the VPN and it still is blocked. Any ideas?

Answers

  • DSherfey
    DSherfey Member ✭✭
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    Wanted to leave an update as I have been working with my VPN provider over the last few weeks. So far they have not been able to pinpoint any reason why the local link connection would be having issues with the VPN connected and routing traffic. Interestingly enough though, just to test a theory, I installed a WiFi extender near where the radio is and when wired directly into that and therefore the network itself rather than as a local link there are no issues.
    For anyone in the future having issues with a VPN and local link connection the solution might just be to network the radio however you are able.
  • DSherfey
    DSherfey Member ✭✭
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    Wanted to post another follow up for anyone in the future dealing with with this. My previous fix with the extender worked fine, but did yield some SmartSDR lag which was rather annoying. I recently redid my home networking moving to an integrated mesh network. Off the mesh node in my office/shack I hard wired a network switch and into that I have hard wired both the computers and the Flex. Not sure if this will improve the lag since both devices are now essentially networked together on the switch or if traffic still has to be directed from the switch to the node and then to the main router node and back. I'd love to hear if anyone knows whether or not networking the computer and radio this way will have the same lag potential or if it's closer to a local link with essentially no lag. That aside I am able to run my VPN and it introduces no issues with SmartSDR seeing the radio.

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin
    edited July 6
    Options

    You might want to look at some tools to actually measure the network latency and jitter.

    I have used iPerf for years. Very very useful as it eliminates a lot of guess work. I would recommend you run it using link.local and over your VPN.

    Take a bit to figure out how it works. For todays Ham who uses networking, it is as valuable as an antenna analyzer.

    73

    https://iperf.fr/

    • TCP and SCTP
      • Measure bandwidth
      • Report MSS/MTU size and observed read sizes.
      • Support for TCP window size via socket buffers.
    • UDP
      • Client can create UDP streams of specified bandwidth.
      • Measure packet loss
      • Measure delay jitter
      • Multicast capable
    • Cross-platform: Windows, Linux, Android, MacOS X, FreeBSD, OpenBSD, NetBSD, VxWorks, Solaris,...
    • Client and server can have multiple simultaneous connections (-P option).
    • Server handles multiple connections, rather than quitting after a single test.
    • Can run for specified time (-t option), rather than a set amount of data to transfer (-n or -k option).
    • Print periodic, intermediate bandwidth, jitter, and loss reports at specified intervals (-i option).
    • Run the server as a daemon (-D option)
    • Use representative streams to test out how link layer compression affects your achievable bandwidth (-F option).
    • A server accepts a single client simultaneously (iPerf3) multiple clients simultaneously (iPerf2)
    • New: Ignore TCP slowstart (-O option).
    • New: Set target bandwidth for UDP and (new) TCP (-b option).
    • New: Set IPv6 flow label (-L option)
    • New: Set congestion control algorithm (-C option)
    • New: Use SCTP rather than TCP (--sctp option)
    • New: Output in JSON format (-J option).
    • New: Disk read test (server: iperf3 -s / client: iperf3 -c testhost -i1 -F filename)
    • New: Disk write tests (server: iperf3 -s -F filename / client: iperf3 -c testhost -i1)

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