Hi,
Thanks for posting!
Typically, when we’re unable to duplicate an external display through the docking station, it is because the graphics card of the system needs to be updated with the latest graphics driver from Dell.
DisplayLink has a support article about this that explains just that: https://support.displaylink.com/knowledgebase/articles/938634-no-option-to-duplicate-monitors-on-windows-10
EDIT: Unfortunately, I noticed you mentioned the Acer system uses Intel HD Graphics 3000. This is one of the older graphics drivers thatdoes not actually have driver support for Windows 10… As a result, it will not be possible to duplicate your external display through the dock.
DisplayLink recommends a workaround of a 3rd party tool to mirror the screens named Actual Multiple Monitors.
Sorry there is no clean solution here. Please let me know if you have any questions.
Thank you!
Mitchell