HDCP issues on Win10

System: Dell Precision 7770
Dock: TBT4-UDZ
Monitor #1: LG 32UL950-W (32" 4K HDCP-compliant) over HDMI
Monitor #2: LG 27UL600-W (27" 4K HDCP-compliant) over HDMI
Intel UHD 12th Gen graphics and NVidia RTX A1000 graphics card
External displays set to run on NVidia discrete card.
Laptop display disabled (laptop closed)

I am unable to play any content while in 4K resolution on my external monitors through the dock which I installed on 4/1/2023. When I fire up Netflix, Hulu, or Prime Video, I get black screens on both monitors. Closing the apps does not restore the screens. Opening the laptop doesn’t restore the screens. Only reboot restores the screens.

Previous to this dock, I used a USB3 dock that ran DisplayLink over the otherwise-identical setup without issues showing HDCP content in 4K.

Do I not have something set up correctly?



Your support email (support@pluggable.com) is rejecting emails with attachments so I am unable to send the diagnostics report:

Remote Server returned ‘552-5.7.0 This message was blocked because its content presents a potential 552-5.7.0 security issue. Please visit 552-5.7.0 https://support.google.com/mail/?p=BlockedMessage to review our 552 5.7.0 message content and attachment content guidelines. f9-20020a17090624c900b00931d1a018casi944772ejb.169 - gsmtp’

Hello George,

Thank you for letting me know. I’m uncertain what is the cause of this email trouble but have started investigating that. I do seem to be getting emails from some other customers alright. A possible workaround would be if you have access to any cloud storage to share the file through. Like Google Drive, DropBox, Microsoft One Drive, etc. If you do you could upload it there, then email us with that link.

Otherwise if we can’t get the diagnostics we may simply need to proceed without and I can try to direct you through checking a few items manually.

Thanks again, and my apologies for this hassle!


The 30Hz refresh issue is fixed. That was a monitor setting on my LGs that I forgot I toggled off in trying to diagnose this issue.

To recap the issue: The desktop works fine (windows, productivity, messaging, etc), but any embedded video or HDCP video causes the monitors to go to black even though the desktop is still functioning (sound, etc). No amount of plugging and unplugging brings the pictures back. Only reboot works. Unplugging the dock from the TBT4 port and opening the laptop dumps all the content onto the laptop main display which then continues to function fine.

Here are my findings thus far:

  1. Disabling Intel graphics does not change any behavior.
  2. Changing HDMI cables does not seem to affect the behavior either. The HDMI cables I am using are the ones that came with the LG monitors so they are only about 2 - 3 years old.
  3. Moving to the DisplayPort cables brings up everything fine, including all video content. However this leaves my desktop computer without connectivity which isn’t an acceptable long-term solution.

Does the dock need some kind of DisplayLink-type driver I’m missing or is that all baked-in without the need for a driver? It’s strange that the DP works fine, but HDMI is a total failure.

New update after some fiddling:

Running one monitor on DP and one on HDMI didn’t change the results.

Turning off use of the discrete GPU (NVidia RTX A1000) on my Dell, I now have both monitors on the dock and running 4K@60Hz with no HDCP issues. However only if the system uses the Intel UHD Graphics 770 GPU.

Previously, I was unable to even bring up the desktops consistently using the discrete GPU and running both monitors at 4K@60Hz. I had to flip one to 30Hz.

Based on the above results and the fact that the DP connection runs both monitors on the discrete GPU just fine (including HDCP), I am leaning to the conclusion that this is a Dell design or implementation issue with the RTX A1000 GPU or, possibly, a limitation of the GPU itself.

One element of my setup that I just realized may be part of the equation: one monitor is landscape and the other is portrait. Internally, I believe this results in NVidia rendering a desktop that’s actually something like 5640px by 3480px because the overall desktop is rendered as a large rectangle, even if not all of it is actually displayed. However I am not sufficiently familiar with how that dovetails to video rendering or HDCP content rendering.

I will update after I consult Dell support in the interests of spreading the knowledge.

Follow up on talks with Dell support:

Dell support kept pointing me to their dock (WD22TB4) as an explanation of my question:

What connections and resolutions does the Precision 7770 with NVidia RTX A1000 support via the Thunderbolt 4 connector?

Based on the responses I received and my own testing, the laptop is limited to a single HDMI output at full bandwidth or multiple DisplayPort outputs at full bandwidth using the NVidia graphics system. When using the Intel graphics system, the displays ran fine (4K@60Hz) in all cases.

The solution I landed on was to purchase two Plugable DisplayPort to HDMI 2.0 Active Adapters (Model DP-HDMI) in order to allow the laptop to utilize the DisplayPort connections of the dock and thereby run my external monitors on the A1000 graphics card at full 4K@60Hz resolution.

Leaving this here in case other Dell users run into the same issue(s) I have, but want to use this really nice dock.

Thanks for the look at the diagnostics Joshua, but I think this isn’t a Plugable issue.

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