My earlier advise about using xrandr is not working for me either
I now have monitors shown as on in xrandr, but they are in fact in power saving mode. All this happens once in a while, when a message appears in kernel logs:
Code:
[18125.523348] usb 4-1.1: Disable of device-initiated U1 failed.
[18125.530395] usb 4-1.1: Disable of device-initiated U2 failed.
[18125.530508] cdc_ncm 4-1.1:1.5 enx9cebe8554690: unregister 'cdc_ncm' usb-0000:39:00.0-1.1, CDC NCM
[18125.582824] usb 4-1.1: Set SEL for device-initiated U1 failed.
[18125.589806] usb 4-1.1: Set SEL for device-initiated U2 failed.
This seems like a device wants to sleep, and the kernel can't prevent it and is losing it. Nevertheless, in a moment it brings itself back to life, with everything connected though it working -- except, alas, for the monitors.