How to set Gnome settings to Screen Blank after 15 minutes inactivity?

Hello guys! 🙂
I used to configure latest Armbian @ Orange Pi 5 B in such particular way: https://dragonserw.ru/arm64:orangepi-5.
The problem is: Gnome settings does not save.
As for now, I extremely need to set my screen off after 15 minutes of inactivity.
How can I do it from command line?

My hardware:

dragonserw@orangepi5:~$ inxi -b
System:
  Host: orangepi5 Kernel: 5.10.160-legacy-rk35xx arch: aarch64 bits: 64
    Desktop: GNOME v: 43.6 Distro: Armbian GNU/Linux 12 (bookworm)
Machine:
  Type: ARM System: Orange Pi 5B details: N/A
CPU:
  Info: 3x 4-core Model N/A [MCP AMP] speed (MHz): avg: 2064
    min/max: 408/1800:2352:2304
Graphics:
  Device-1: display-subsystem driver: rockchip_drm v: N/A
  Device-2: mali-bifrost driver: mali v: N/A
  Device-3: rk3588-dw-hdmi driver: dwhdmi_rockchip v: N/A
  Device-4: Logitech B525 HD Webcam type: USB driver: snd-usb-audio,uvcvideo
  Display: x11 server: X.Org v: 1.21.1.7 with: Xwayland v: 22.1.9 driver: X:
    loaded: modesetting unloaded: fbdev dri: rockchip
    gpu: rockchip_drm,mali,dwhdmi_rockchip resolution: 1080x1920~60Hz
  API: OpenGL Message: Unable to show GL data. Required tool glxinfo
    missing.
Network:
  Device-1: Broadcom driver: pcieh
  Device-2: rk3588-gmac driver: rk_gmac_dwmac
  Device-3: wlan-platdata driver: wlan_platdata
Drives:
  Local Storage: total: 232.97 GiB used: 20.11 GiB (8.6%)
Info:
  Processes: 321 Uptime: 13h 2m Memory: 15.6 GiB used: 3.08 GiB (19.8%)
  Shell: Bash inxi: 3.3.26
dragonserw@orangepi5:~$ 

Edited October 1, 20233 yr by SerW