WSUS - how to force install of updates and restart?

Question

Since some users rather send their computers to sleep than restart, updates are massively delayed to be installed.
I changed our GPOs but still can't force the restart in a timely manner. What I'm most confused about: with the settings I will present you, it was planned that clients install at 12:00 (noon) and then have a maximum delay of 3 hours until they restart, nagging the users all 15 minutes that a restart will occur.

Clients: Windows 10 21H1 / 21H2
Server: 2019

What happened:

• until 12:00 the Windows Updates in Settings told me that an installation was scheduled : good!
• At 12:00 the updates were installed: good!
• NO notification after that (except the small icon in the taskbar that the computer is missing updates)
• When I check Windows Updates in Settings, im told the restart will occur at 3:00am: why!?

GPOs

• Allow Automatic Updates immediate installation (has nothing to to with the problem, just to include that I use that setting)
• Always automatically restart at scheduled time: Restart Timer: 180min
• Automatic update detection frequencey: 2 hours
• Configure Automatic Updates: 4 - Auto Download and Schedule installation
  Install during automatic maintenance: every day, 12:00 (noon), every week
• Configure auto-restart reminder notifications for updatesPeriod: 15min
• Configure auto-restart required notifications for updates Method: 2-user action
• Display options for update notifications: 1-Excluding all notifications, excluding restart warnings

My goal would be, that updates get installed immediately when they receive them from WSUS and then get a warning every 15min that a restart will occur latest in 3 hours.I think that's not possible, so 12:00 installation and then 3 hours warnings and then restart would also be ok. What settings do I need for that and why don't the users see no restart warnings and restart is scheduled at 3am with my settings?