VK6KCH

Hi John and Thierry,

Thanks for your replies. The KiwiSDR is behind a 4G router, so there's a stage of outbound NAT there (with no explicit port forwarding to handle inbound connections), and then on top of that, the 4G router is only assigned a CGNAT IP address, so there's another stage of NAT occurring on the cellular service provider's edge. I had assumed that only outbound TCP sessions would work, and that attempts to initiate inbound traffic (TCP or UDP) wouldn't work, thanks to the NAT barriers (especially the cellular service provider's edge)... hence the beauty of the proxy service! It was all working fine up until recently, so the overall architecture is viable.

I suspect that an outbound TCP session from the KiwiSDR to the proxy server has collapsed and not been reestablished? Or, is it even a UDP "session", rather than TCP? (I'm now wishing that I'd inspected the traffic with wireshark earlier, but I was focused on the RF side of things).

In the short term, I'll just have to hope it fixes itself, but I'll try to get back to the remote site in the next week or two and try rebooting the KiwiSDR whilst keeping the 4G router powered up. (I wonder if the issue was caused by the whole system being power cycled as part of the changes I was making, and a race condition being entered that has messed up the NAT table, especially as the 4G router has a habit of connecting to the cellular network for about a minute, then disconnecting and reconnecting again soon after... did the KiwiSDR establish the outbound NAT during the first short connection window, but it's not honoured during the currently established connection?)

In the longer term, I wonder if there's a way that the KiwiSDR can detect that the connection to the proxy service is a bit of a zombie, and then clear it down and rebuild it, or even force a complete reboot, to try to reestablish service? (If that feature is enabled... don't want to be rebooting any completely standalone installations that are only meant to be used locally!)

73,

Chris