I have a MacBook Pro 15, with touchbar, connected via DisplayPort to a Lenovo LI2821 4k monitor . I also have an USB connection to the monitor. The USB for access to the integrated webcam, USB hard drive, speaker and mic.
When the MacBook Pro is first connected all of the devices work properly. After a short period of time, the speaker and mic stop working. For example, when viewing videos from YouTube, the video fails to start and I get the following message:“If playback doesn’t begin shortly, try restarting your device”. When I change the audio output from the USB audio to the DVI audio, the video starts immediately.
When I go into System Preferences, Sound and test the mic, there is no response. If I change that input to the Internal Microphone, that device works.
Thank you for posting, and I would be happy to help with your new docking station!
Thank you as well for the excellent detail you provided about your setup, how things are connected and the behavior it is all much appreciated.
While I cannot be sure, it sounds like (no pun intended) that there may be a specific incompatibility between the USB-connected devices in your monitor and one of the USB 3.0 Host Controllers in the dock.
To expand further, there are two USB 3.0 host controllers within the dock, one made by Asmedia and the other by Fresco. The single USB port on the front of the dock and the two top-most ports on the back (assuming the dock is oriented vertically) are routed to the Fresco controller. The remaining two USB ports on the back, closest to the dock’s Ethernet port, are routed to the Asmedia controller (example photo with this highlighted below).
When USB devices are not working as expected, switching to a different USB 3.0 controller can sometimes help. Can I ask you to switch which USB port (and in effect USB controller) you are connecting the monitor to, to see if that changes the behavior?