P3421W, KVM issue, MacBook Pro

Question

Hi,I've just installed the Dell P3421W with a desktop PC on the HDMI port and either my 2017 MacBook Pro (with macOS Monterey) or my new ThinkPad T14 on the USB Type-C port. Both laptops seem to charge OK and the 4K native video also works OK and looks good for what I need.The built-in Dell P3421W KVM has my Corsair keyboard and SteelSeries mouse on the inputs. Switching the video input also switches the input devices. Although there are no issues with the ThinkPad T14 (and the same for my desktop PC), there is an issue with the MacBook Pro where the keyboard and mouse become unusable immediately or soon after changing to them.The lights stay lit on the keyboard but they do off on the mouse.I attempted to install the Dell DDM on the MacBook Pro but it's probably not supported anyway. However, it shouldn't be needed to switch USB inputs as I've configured the monitor to do this.Please does anyone have any ideas about how to fix this ? Thanks

netdudeuk · Answer

Thanks for the prompt reply.

The MBP only has USB-C ports. I do have adapters so I could try connecting the monitor Type B to the MBP but then what where on the monitor would I connect my desktop PC USB port ?

DELL-Chris M · Answer

I do not see any macOS drivers or macOS firmware on the online P3421W drivers page. So you are correct that the offered DDM will not work. Based on your testing, we know that the P3421W KVM is functional on a hardware level.

Does the 2017 MacBook Pro have the old USB Type-A port? If yes, can you try connecting the P3421W USB Type-B to USB Type-A upstream cable?

P3421W USB Type-C --> USB Type-C to C cable --> 2017 MacBook Pro USB Type-C
P3421W USB Type-B --> USB Type-B to USB Type-A upstream --> 2017 MacBook Pro USB Type-A

netdudeuk · Answer

I did the test where the monitor Type B was connected to another USB-C port on the MBP.  It made no difference to the outcome.

netdudeuk · Answer

Dell, please ? Thanks.

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