External Monitor Going To Sleep Causes Screens To Wake

I didn’t have much issue with the previous monitor I had but my new one is not going fully to standby mode. It works fine on Windows (dual-boot).

I have a Philips PHL 246E9Q connected to my laptop via HDMI. When it tried to put the monitors into sleep the laptop screen turns off fine but the external monitor will attempt to go to sleep (screen will go black and message saying no signal, going to sleep mode), but just as the monitor goes to sleep it wakes; The laptop screen and monitor come back on. Sometimes the laptop screen will go to sleep but the monitor never does.

Hmm, I have nearly identical symptoms on completely different hardware: desktop, only one monitor, displayport connection. I’ve had this issue with different monitors, video adapters, and desktops (X11 & Gnome 4x) over the years. It seems to come and go. I was hoping it would stop after I upgraded to F38, but no joy.

I’ve never understood what causes this, and I don’t know where to start to troubleshoot it.

Hmm, have you noticed that it doesn’t always come back on immediately? There is a small delay between the monitor’s “no signal” message and the message that a signal has been restored and the monitor wakes up. That’s my symptom. I think I know what it is, too: it’s the change of the time. The lockscreen has shows the time, and it seems to wake up when the time is changed, which happens at the start of the next minute. Does that make sense? Can you tell if this is the same for you, @jimbo2150 ?

No, I’ve not seen this. Nothing related to the clock.

Just that both screen wake the moment the external monitor actually goes to sleep (after it displays the “turning off screen” message and the screen actually goes into sleep mode). After that it seems like the computer recognizes there is an issue and the laptop monitor will turn off without the external monitor ever going to sleep again (until next boot).

Likely part of the same issue, but sometimes when it is rebooting/shutting down there will be a delay. It will say the “shutting down” or “rebooting” message but will not actually reboot/shut down until the external monitor goes to sleep. It’s like it gets “stuck” until the monitor shuts off.

Ah I think I misinterpreted your description.