Thanks for the example. According to the server logs, that spot was delivered to you (among others):
So I’m inclined to believe that something went wrong on the Telnet client side, which is the only action that you have enabled for that trigger. It could be an idle timeout issue – before the 19:05 spot, there were no spots sent to you for slightly more than an hour. Some firewalls/routers/CGNAT implementations terminate idle TCP connections after a short time, sometimes only 5 minutes. When the connection is shut down uncleanly (and most firewalls simply delete the state table entry, without notifying the client or server), it can take a while for the Telnet client software to notice. If a spot comes in during this interval, it will not be delivered to the client. The client software could issue a “sh/dx” command after reconnecting to grab the last 20 spots or so to catch up, but not all clients do this.
What I’ve just done is enable server side TCP keep-alives with a one minute interval, in an attempt to stop intermediate firewalls from breaking idle connections. Hopefully it works…
If you have important spots that you don’t want to miss, then I’d suggest also enabling the App action to get those on the HamAlert app, which does not have these idle timeout issues.