USB-C DisplayPort Alt external monitor stops working after BIOS update?

[TZRick]

Hi everyone,

I have my laptop connected to a 24" Dell monitor via USB-C to a Lention CB-D53 dock via the dock's HDMI port.  Also connected to the Dock is the monitor's USB hub and from there, my wired USB keyboard and mouse.

A few days ago, the laptop stopped displaying on the external monitor.  When I go into Windows display settings, either the monitor is not present or it is present, but does seem to be corrupt (shows as 800x600, but the model, etc. appear).  No picture appears on the external monitor regardless, even though some apps seem to be positioned there (and thus invisible on the built-in monitor).  I also tried with two of the Lention docks (they sent a second as the ethernet has been spotty with the original), but the experience has been the same.

At first I thought there was some fatal flaw with the dock, but I just plugged-in my daughter's 2020 Dell Inspiron and the picture showed-up fine on the external monitor.

So at this point, I have to conclude that the Envy laptop is the culprit.  It's possible the issue was caused by the HP System BIOS Update for AMD processors (F.02) that was installed on Jan 16th.  But I have no clue how to move forward from here.

Any ideas?

Thanks in advance!

[itsmyname]

@TZRick -- your laptop has one:   USB Type-C 3.2 Gen 2 (10 Gbps), Power Delivery (PD), DisplayPort, Sleep and Charge

So, does your monitor have a DisplayPort video-input?

If so, connect a cable from the above USB socket to your monitor, to see if this "limited" configuration works.

[TZRick]

@Itsmyname:  I'm not following you.  Yes, the monitor has DisplayPort input but I don't have a DisplayPort to USB-C cable to connect it.  I guess I can get one, but the problem is my KVM only uses HDMI, so I would have to change a good bit of my equipment for something that really should work.  I also have USB and ethernet running off the USB-C cable via the dock.

[itsmyname]

@TZRick -- I suggested something simple to try, to see if connecting directly from your laptop to your Dell monitor would work, namely that your laptop would detect the external monitor when it is not connected through the dock.

For a USB-c to DisplayPort cable, see: https://www.amazon.ca/Displayport-QGeeM-Thunderbolt-Compatible-MacBook/dp/B07V2ZM8DF/ref=asc_df_B07V...

Also, there do exist video-cables that are DisplayPort at one end, and HDMI at the other end.

What inputs does your Dell monitor have? DisplayPort? HDMI? VGA? 

Instead of using your KVM to switch the video-signal, use the monitor's OSD (On Screen Display) to switch video-inputs.

Is this a matter of powering-off your laptop, your dock, and your Dell monitor, and then powering-on in this order: Dell monitor, dock, and finally the laptop?