I have an HP Zbook running Ubuntu 20.04, which I would like to connect to two HP 24es monitors that I have at work. Since the laptop has only one HDMI output, I connect the second monitor using the UBS-C output and a USB-C to HDMI adapter. However, while the monitor connected via HDMI works fine, the monitor connected through USB-C generally fails to give a picture.
Interestingly, the monitor is recognized by Ubuntu, i.e. I can see the monitor in display settings and change its resolution etc. I have found that if I lower the resolution to something like 800x600, the monitor will work. If I then turn the resolution back up to 1920x1080, it will sometimes suddenly work, and I can use the monitor perfectly until I unplug the cable. Mostly however, it either turns back off or it shows a screen full of coloured horizontal bars, like the signal is not coming through correctly. If I keep flipping the resolution back and forth then after a couple of tries I usually get "lucky", and it works.
I haven't been able to find a better fix for this problem. I am currently using the Nouveau display driver, but installing the proper NVIDIA driver does not change the behaviour at all. If I boot my laptop into windows, the problem is gone completely and the USB-C output works fine, so it does seem to be a specific problem with Ubuntu. Does anyone know what I could try?
Thanks!
