Tip - if HDMI doesn't work, make sure your USB-C cable is the right kind

I returned from vacation and couldn’t get the HDMI working on my UD-ULTC4K. The DisplayPort worked fine, as did the ethernet, keyboard, and power. But the HDMI wouldn’t work. I tried re-installing the DisplayLink drivers, etc. - nothing worked.

Then I realized that the USB-C cable I was using wasn’t the one that came with the UD-ULTC4K. I switched to that cable, and now everything works as before.

I don’t know the exact specs of what kind of cable is needed, but I do know that all of the other USB-C cables I had - even the one that came with my Macbook Pro - wouldn’t work.

Perhaps this will help someone else.

Thanks for calling attention to this, Sam!

One of the most challenging aspects of USB-C is how laptop and cable manufacturers can choose to support (or not support) specific features.

As you mention, the Apple USB-C cable included with the new MacBook Pros – and many others – doesn’t support native “USB-C Alternate Mode” video, which is used to enable the HDMI port on our USB-C docks.

We do try to call attention to the importance of using the included USB-C cable in our post-order email and on the product page FAQs, but these details can be easy to overlook.