“Driver missing,” Alex muttered.

First stop — the manufacturer’s website. Long defunct. Domain parked. Wayback Machine showed a 2014 download page with broken links.

COM5 available.

Second stop — generic USB-to-serial drivers. PL2303? No. CH340? No. FTDI? The device wasn’t recognized at all.

A deep breath. Then a test loopback: sent AT . Received OK .

The LED blinked twice — then stayed solid green.