DP 1.4 KVM Switch - Dual Monitor with Mac Mini and MacBook Pro 2019

Hi there,

I finally received the new DP 1.4 dual monitor KVM after few months of waiting.

First impression is really positive. Image quality and refresh rate are impressive but I am having some issues using with two macs.

The first problem occurs when I disconnect the MacBook from the KVM and even if I plug it back after few minutes the KVM switch its mode from dual monitor to single monitor. When I get to this state I am completely lost and not sure what to do. This happened to me already and I managed to resurrect it by disconnecting the unit from the power for half day and it came back as expected after that. Unfortunately, the next day this happened again and I have not managed to bring it back yet. I disconnected the power few times and swapped the cables with no good result. What am I supposed to do to bring it back the kvm to dual monitor mode? To be precise I am not using two monitors but the PBP mode on the Samsung C49RG90SSU. Single monitor but in dual screen mode

The second problem is around the fact every single time I switch between macs my workspace rearrange itself left and right. It is frustrating that I need to rearrange them every time I swap. I was aware this is an issue you tried to fix when building the unit, however, I was not expecting to be that bad. I am really keen to find a solution for this issue either at software or hardware level. I have read people are using some DP repeater adaptor to avoid the mac to identify the monitor as disconnected but before I spend a fortune in buying a repeater for each of the four cables I would like to double check what is your opinion in this regards and whether you have any advise you can give me to have a perfectly working and RELIABLE setup. I prefer to spend a bit more rather than having regret later with some hacky solutions.

Despite the two problems above I want to clarify I tried many kvm before and this is the best product I have put my hands on to date. Nice work guys

Thanks for you help

I will write down my setup if you need some extra information:

Samsung C49RG90SSU - CRG9 Series - QLED monitor - 5120 x 1440 Dual Quad HD used in PBP mode

Cables for MacBook Pro 15": 2 x YIWENTEC USB C to DisplayPort 1.4 8K Cable with USB-C PD 8K@60Hz

Cables for Mac Mini: 2 x CHOETECH USB C to DisplayPort Cable 4K@60Hz(Thunderbolt 3 Compatible)

Cables from monitor to KVM: 2 x ANNNWZZD 8K DisplayPort Cable V1.4,Copper Cord Ultra HD DP TO DP CABLE supports 8K@60Hz 4K@144Hz 32.4Gbps

If I might ask, why pbp mode? it seems like with this setup you could just run with a single cable?

You might try mixing one of each type of USBC to DP cable, so each mac has one of each. I wonder if there is some weird edge case where the monitor seems to be the “same” but isn’t.

That’s a cheaper repeater that may be worth trying. I don’t know that it will tell the mac a monitor is always attached, though.

You might try stay:
https://cordlessdog.com/stay/

it will save and restore window positions on the mac.

If you unplub both USB (A to B) and the power brick from the KVM, it should reset within ~30 seconds. On macs, if it struggles to handshake with a display, it gives up

You can also set a hotkey to toggle mirroring on and off, which is sometimes enough to get macos to start trying to handshake with the display again.

What might be happening is your USBc to DP adapters may not properly sense the display has been “unplugged” when switching away on the KVM, and may not handle that case well. In that case power-cycling the usbc to DP adapter by totally unplugging them, then plugging them back in, may do it.

Some of these adapters “sense” the display is attached by checking the case ground against a ground pin of the monitor, rather than via handshake. When the KVM switches away from the usbc monitor, the usbc adapter doesn’t know how to handle it, and that can get the mac into the “frustrated” state trying to shake hands with a monitor that isn’t there (when the usbc adapter is there, and is doing part of the handshake).

So maybe swap around two of the usbc cables and see if that does anything?

in PBP mode, you probably aren’t using the DP1.4 bandwidth anyway?

Wendell

Thanks a lot Wendell,

Switching the cables did the trick and it now looks much more stable. I am now able to reset the KVM as well. I was not disconnecting the USB cables which was not triggering the full reset.

I am still trying to find a solution for the screens which are switching their position. I see this more frequently on the Macbook than of the mac mini. The Stay software is more for fixing windows on the screen but my issue is with the screens themselves inverting.

To be clear I am going to attach below my screen setup

Before I switch below how my desktop looks like

ad this is after


As you can see the screens switch left and right and I am not sure how that can happen. I guess it is the PBP mode but I am not sure.

The reason why I use the PBP mode is because the image quality is much better on the mac mini than by using a single cable. Apple does not really support very well 5120 x 1440 and even if the resolution is supported the image quality is very blurry. I also prefer to manage the full space by diving the monitor in two screens which helps with screen sharing and with window management. In terms of refresh rate I am happy with the 100hz provided by the PBP mode and if I play games I just switch the cable so it is not a big issue. I use the monitor more for work reasons than for gaming so I am ok with that.

Thank you
Tanio

try swapping the cables going into the kvm from the mac, as dumb as that sounds?
is the order random, or consistently backwards?

I tried the Cable Matters DisplayPort Repeater with the DP KVM switch.
It did not work. The repeater did not feed EDID to connected systems for KVM switch.

did you complete this procedure?

hook up
PC > Repeater > Monitor

set the desired refresh and resolution. Press and hold for 4 seconds the button on the repeater. Wait for the lights to settle down after that.

Then unplug the repeater from power and hook up as:

PC > repeater > Kvm > monitor.

Plug power back into KVM and repeater. Do not press button!

Oh, cable matters repeater. Yeah, the CM one doesn’t retain the EDID when it is inactive. The level1techs one does. The CM one is okay but when your PC goes link dead, it tells the monitor. The CM one is good for marginal devices or devices like the trashcan mac

There is no button on the repeater. How can you “press and hold” for 4 seconds the button on the repeater?

I thought you meant a different model, sorry. the level1techs kvm has the button

This topic was automatically closed 273 days after the last reply. New replies are no longer allowed.