Poly P21 on Windows 11 - webcam works but no display

[barry253]

After not using this monitor (Poly P21) for a few weeks, I'm having trouble getting it reconnected.

I'm using the USB-c to USB-A cable, with the A side connected directly to my Dell Latitude 5420. This configuration previously worked fine.

Now, when connected, Windows plays the chime, but the monitor does not show up as an additional display, and nothing appears on screen.  The webcam and speakers/microphone work as expected. The Poly has power and lights on the side and volume buttons on the bottom work, so it has power and connectivity.

Poly Lens shows the monitor as connected - but occasionally shows "not connected". The webcam listing always shows connected.

Device Manager under Display adapters correctly shows "Poly_Studio_P21_Display".

Troubleshooting steps already tried:

- unplugging and rebooting

- disabling and re-enabling the display driver

- uninstalling all Poly software and DisplayLink drivers, and re-installing latest versions

Same result. Any suggestions appreciated.

[SteffenBaierUK]

Hello @barry253 ,

Welcome to the HP Poly community.

I assume you did install the Display Port drivers as required and it should display a message on the screen to remind people.

Try the search as this has been answered many times before.

Example: 

- Re: Display Link Driver download link for Poly Studio P21 - HP Support Community - 9432991

Best Regards

Steffen Baier

[barry253]

Yes - I uninstalled and re-installed the DisplayLink driver package.

The monitor shows up correctly in Device Manager, under Display Adapters as "Poly_Studio_P21_Display."
Drive manufacturer shows as "DisplayLink" with the following Hardware IDs:

USB\VID_17E9&PID_FF18&REV_3038&MI_00
USB\VID_17E9&PID_FF18&MI_00

[barry253 · Accepted solution]

I solved this and want to share the solution for anyone who runs into it in the future:
Windows has a setting in Display Settings->Advanced Display called "Remove display from desktop", which was enabled for this screen for some reason.

Since the screen is disabled in Windows, it won't show up in Display settings as an available monitor, so go into Advanced Display for a different screen, and then select the hidden screen from the dropdown on top to get access to the setting.