Mac Extended Display Through DP AltMode Dock

[MozMan68]

My issue is a little bit different than other similar posts...so here goes...

I have a Samsung Ark display that I was using with my gaming rig and my MacBook Pro (16" with M1 Max). Both the laptop and PC were connected directly to the monitor with HDMI cables and worked fine, although the Gen 1 Ark only allows one source at a time to be displayed on the screen (not an issue for me).

I have since added a docking station that utilizes DP Alt Mode and should work fine with the Mac. It does power the Mac, allow data transfer through the dock to thumb drives, and it SEEMS to connect to the Ark as when I plug in the cable, the Ark is recognized in the display settings...BUT...no image, and the monitor eventually wants to go to sleep.

I know the video connection is fine even though I need to use a DisplayLink to HDMI adapter for the dock as I plugged in my Dell laptop and everything worked fine.

There has to be some setting on the Mac that is preventing the video signal from going through the dock and to the monitor, but I can't figure it out (yes...I use a Mac, but limited knowledge on MacOS frankly). Thanks in advance for any advice!

 

[JonnyMacx86]

Have you tried closing the Mac lid to see if the Samsung Ark lights up then? You may need an external keyboard or pointing device to wake the Mac up when it's in clamshell mode. If, after doing that it doesn't output to your display, it would isolate the docking station as the issue. Sounds like a hardware limitation to me rather than something you're doing wrong, but do the above to be sure.

 

[MozMan68]

Have you tried closing the Mac lid to see if the Samsung Ark lights up then? You may need an external keyboard or pointing device to wake the Mac up when it's in clamshell mode. If, after doing that it doesn't output to your display, it would isolate the docking station as the issue. Sounds like a hardware limitation to me rather than something you're doing wrong, but do the above to be sure.

I think that's usually the opposite problem, no? Monitor isn't on BECAUSE the Mac Book is closed and asleep? Mac Book is always open in my case as I use the Ark as an extension of the display.

The Mac Book and monitor have always worked with the HDMI directly connected...and the Mac Book DOES show the Ark as an external monitor. The monitor is just not getting the video signal through the docking station despite all monitor and Mac settings I know to play around with being correct.

 

[JonnyMacx86]

I think that's usually the opposite problem, no? Monitor isn't on BECAUSE the Mac Book is closed and asleep? Mac Book is always open in my case as I use the Ark as an extension of the display.

The Mac Book and monitor have always worked with the HDMI directly connected...and the Mac Book DOES show the Ark as an external monitor. The monitor is just not getting the video signal through the docking station despite all monitor and Mac settings I know to play around with being correct.

Closed, yes. Asleep, no. With an external keyboard and/or mouse, you can wake a closed MacBook. Just curious to see if it's indeed a limitation of the dock or something else.

 

[MozMan68]

Closed, yes. Asleep, no. With an external keyboard and/or mouse, you can wake a closed MacBook. Just curious to see if it's indeed a limitation of the dock or something else.

Yep...I tried it...no go...(I do use a magic mouse/keyboard combo all the time in my office).

The dock works fine with the existing cable connection when the USB-C connection is connected to my Dell.

The monitor/Mac combined has and does work fine when connected directly to the HDMI port on the Mac.

The Mac does recognize that it is connected to the monitor when the USB-C cable is connected, but just no video display...weird. Thanks for the input!!

 

[JonnyMacx86]

Sorry! I'm stumped

 

[molmac]

I stumbled across the same problem with my HP dock G5. The screen was recognized and powered on but no video troughput. Updating to 14.4.1 seems to have fixed this behaviour for me.

from Apple:

macOS Sonoma 14.4.1​

This update provides bug fixes for your Mac, including:

• USB hubs connected to external displays may not be recognized.

Also you can try to set Allow accessories to connect to Always under System Settings > Privacy & Security
This may prevent usb devices from being disconnected when the macbook is locked.

Hope this helps.

 

[MozMan68]

I stumbled across the same problem with my HP dock G5. The screen was recognized and powered on but no video troughput. Updating to 14.4.1 seems to have fixed this behaviour for me.

from Apple:

macOS Sonoma 14.4.1​

This update provides bug fixes for your Mac, including:

• USB hubs connected to external displays may not be recognized.

Also you can try to set Allow accessories to connect to Always under System Settings > Privacy & Security
This may prevent usb devices from being disconnected when the macbook is locked.

Hope this helps.

Great info…thanks! Will try that this morning.

I also have a a new DP to HDMI cable coming as I’m wondering if there is a frame rate issue with the adapters I originally got.

 

[MozMan68]

Issue solved!

Not all DisplayPort to HDMI adaptors are created equal.

Despite purchasing what I thought was an overkill 8k adaptor plug, my replacement 8k cable apparently handles 60fps and the plug only 30fps. That made the difference and the dock works fine.