Thunderbolt

Thunderbolt is a connection technology that carries display and other data through a shared link. Modern Thunderbolt connections use USB-C connectors, but a USB-C connector alone does not identify a Thunderbolt connection.

A dock's display outputs can follow different paths: a native display connection, an adapter, or a USB graphics technology such as DisplayLink. These paths have different scaling, bandwidth and device-command capabilities.

Check the Mac, dock, cable and display together when diagnosing an output. See USB-C, DisplayLink, Link bandwidth and Intel's Thunderbolt overview.