What is USB Alt Mode?
USB Alt Mode is a functional extension of USB-C which enables the USB connection to carry non-USB signals. Alt Mode(s) are optional capabilities that are unique to the USB-C connector or port that allow technologies, like DisplayPort and Thunderbolt 3, to be transmitted. This is supported by the Logi Dock’s supplied cable for connection to a PCs ‘USB C Thunderbolt port*.
* Please plug the supplied cable into the USB-C upstream port (with a purple ring).