Windows 10: Unable to output video signal to an external monitor. Both the notebook and the monitor...

I have been using a combination of Razer Blade Stealth 2018 and BenQ XL2411T for 4 years now when one day my monitor declared that there was no signal. Having done some troubleshooting I thought it was a cable that had died, so I replaced it - that did not fix the problem. So I started mixing notebooks, cables, and monitors to figure out where the issue lays. And it turns out that my laptop works just fine with 2 other monitors over both HDMI and USB-C connections. Furthermore, my monitor receives video signals just fine when they are coming from devices other than my laptop. I feel like I am

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[20H1]Monitor speaker had no sound output after a external monitor is connect to my notebook unit

During using the latest generation intel platform notebook unit, the unit is installed 20H1(windows 10 v2004) OS

connect a external monitor to the unit by type-c port

Then switch the display to monitor only(second screen only),it can be found video can be switched to monitor.But no sound can output from monitor speaker.

Unplug and insert the monitor again, can not recover

Restart the unit, can not recover

change the different monitors to the same type-c port, also lost function(no sound output from monitor speaker)

if this symptom is OS issue ?

please help to clarify it and how to recover

thanks very much!

More info:

1.my notebook use the MSFT inbox driver("Microsoft Inbox Audio Class Extension (ACX) Display Audio Codec Driver (DAC)" :AcxHdAudio.sys) as display audio driver

2.when symptom occurred, no speaker output device can be found on sound control panel(no monitor speaker endpoint showup)

 

Win-10 Pro USB-C video output to desktop monitor

Thanks for the resources. I'm getting a feeling that this particular unit's USB-C port may not have Alt-mode and so might not support video output. But I'll review all the resources and look into it further.

<Hours later>
I've looked into the notebook computer some more and realized that I had forgotten it has HDMI output since I don't actually handle the unit directly much due to most of the time running a local Windows remote assistance window to the notebook so that the notebook is mostly used as a CPU box while its contents are displayed within a Windows remote window on the external Q-HD desktop display on another Windows desktop computer, and the notebook's display is closed most of the time during operation.

Since it would be quite simple to connect HDMI output to the HDMI input of the desktop high resolution Q-HD display, and the fact that the notebook's Intel UHD Graphics 620 chipset and its control panel under Win-10 has a section which allows initiating multiple monitor detection, my guess is that when connected, the external monitor should be detected and at that point the video output could be selected to output to an external destination via settings in the Intel video control panel on the notebook. This should look promising for playback of HD signals such as commercial BDs, if required, from the notebook.

 

After Windows 10 upgrade external monitor does not initialize.

After upgrading from Win 7 to Win10, my 4K monitor connected via display port no longer works. My notebook with lid closed was configured to send video to external screen at 4K resolution. Now, the signal goes to the external screen I hear a pop and the
screen shows No signal to display port. The desktop appears on the notebook screen the pops and tries the external monitor...

Any idea how to resolve?