HKS203-P24 Switching intermittent wrt Intel-based 2019 16" MacBook Pro

Bentley

2025年11月13日 00:13

I have an HKS203-P24, 3 monitor, 2 computer KVM switch. I'm using a MacBook Pro 2019 Intel 16" on CPU 1, and a MacBook Pro 2020 M1 on CPU 2. The Intel MBP has a USB-C to dual HDMI DisplayLink adapter, and the M1 MBP has a USB-C to quad HDMI DisplayLink adapter (using three of the four HDMI sockets). Both adapters are between the laptops and the TESmart KVM.
The M1 MBP handles the video selection switch just fine. The Intel MBP handles video selection pretty well if the clamshell is open. The relative positions of the monitors displaying the desktop move around after each switch, though. If I close the clamshell, the Intel displays appear to have more of a syncing issue when that machine is selected using the KVM; parts of the desktop periodically jump between monitors, and they just don't settle down.
Is this an issue with a combination of the EDID support by the KVM and the relative age of the Intel laptop? I can go out and get some passthrough dongles to try and nail down better behavior from the Intel MBP if it'll help. 

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  TESmart.02

  2025年11月13日 03:48

  Dear Bentley,

  Thanks for sharing the detailed setup and behavior — this is a helpful description.

  When the lid is closed, macOS clamshell mode becomes sensitive to brief signal drops, so it may re-detect the displays, causing flicker or shifting layouts. The M1 MacBook works fine because it uses a newer DisplayLink driver and more stable display handling.

  Recommended steps:
  1. Update the DisplayLink driver to the latest version.

  2. Keep the Intel MacBook lid open to confirm it’s a clamshell issue.

  3. If possible, use native Thunderbolt-to-HDMI adapters for better stability.

  Looking forward to your reply.

  Best regards,
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  Bentley

  2025年11月13日 16:49

  I'm replacing the Thunderbolt/USB-C to Dual HDMI DisplayLink adapter, going with a couple Thunderbolt/USB-C to single HDMI 2.1 adapters, one with Power Delivery. If the EDID confusion doesn't resolve, I'll try adding HDMI EDID passthrough plugs, since the desktop is usually completely confused when I switch back to that machine after a couple hours. We'll get this setup to settle down somehow :)
  
  -Mike

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  TESmart.02

  2025年11月14日 00:44

  Dear Bentley,

  Thank you for the update. Moving from a DisplayLink dual-HDMI adapter to native Thunderbolt/USB-C to HDMI 2.1 adapters is a strong technical improvement. Native DP Alt Mode avoids USB-driven display virtualization and greatly reduces EDID renegotiation and hot-plug events during KVM switching—issues that commonly affect Intel-based MacBook Pros.

  If any display instability remains, adding HDMI EDID passthrough modules is a reliable next step. These ensure a constant EDID signal so macOS won’t re-enumerate or reorder the monitors after sleep or long idle periods.

  Looking forward to your reply.

  Best regards,

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