Hello,
the CAC-1051 did not support a resolution greater than 1920x1080. The CAC-1051 is installed between Lenovo P51 Workstation Dock (DisplayPort) and Uniclass KVM-Switch AL-834ASK (DualLinkDVI).
The problem was solved with newer firmware for the CAC-1051 (version 2.33 instead of 2.19).
Source: /thread/cac-1051-screen-flicking-and-shifting-dp-to-dvi-dl-active-adapter/
Is there a newer firmware version?
Sincerely
Holger Klinge