I've tried two "cheap" converters.
The black one, recognized by system as:
Bus 001 Device 010: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
Sometimes received data are corrupted (random characters). Converter is unable to send valid data.
The blue one, recognized by system as:
Bus 001 Device 009: ID 1a86:7523 QinHeng Electronics HL-340 USB-Serial adapter
This one is unusable. Receives random sequence of spaces, tabs, and line feed characters.
Both converters works fine using 9600 baud.