The Plugable UD-ULTCDL docking station does not support 3440x1440 resolution on any of its display outputs.

Even though the HDMI 1 port supports resolutions up to 3840x2160 at 30Hz, it does not 3440x1440 at any refresh rate. When connecting a monitor with this resolution, the system will not see 3440x1440 as an available resolution, and typically default to a lower supported resolution.

For full support of 3440x1440 displays, we recommend using an alternative dock that supports up to 4K (3840x2160) 60Hz (e.g., UD-ULTC4K).