I have written software called Bedtime to allow parents control over their children's bedtimes by automatically disconnecting their devices from the Internet when it is time to sleep. The software is free and open source.
It installs on a spare computer, or a Raspberry Pi and is targeted at parents with little technical expertise. You control Bedtime through a web browser on your computer, iPhone or iPad.
I'm hoping this will be of use to fellow parents. Please try it to see if it fits in your parenting toolkit. Any feedback is welcome.
Bart...