You shall try setting a lower resolution output (such as 720p or 1080p) and then reconnecting to the KVM switch to test if the monitor displays an image. If it works with the adjusted resolution, it might be an issue with resolution compatibility. Check your monitor's manual for true specs; manufacturers may advertise misleading refresh rates. Use quality adapters from the Avico Approved Adapter List. "To. When I plug the monitor directly to the computer, I can use up to the maximum resolution of 3840 x 2160.