Related search suggestions (useful next queries): I will provide related search terms for further research.
He found an old bookmark pointing to a decommissioned Cisco support mirror. The link was dead. He tried a cached version of a Russian networking forum. There, buried in a thread from 2022, was a link labeled simply: UPD: ASR9XX_USB_Drivers_Final.zip asr9xxusbconsoledriverszip upd
screen /dev/ttyACM0 9600