Some Qnap appliances come with 3.5mm (headphone/jack) ports for serial console connection. If you don't have one and are handy with a soldering iron the pinout is as below to make one up to be connected directly to a computer DB9 port.

For further instruction on connecting please see the Qnap FAQ article 'How do I enter BIOS and Console with 3.5mm' Console port? https://www.qnap.com/en/how-to/faq/article/how-do-i-enter-bios-and-console-with-3-5mm-console-port



Jack
DB9 Female
DB9 Pin Desc
Tip
2
Transmit
Ring
3
Receive
Sleeve
5
Ground