Easiest way to do this: Turn the modem off after bed time (you will also lose internet)
Most expensive but still easy way to do this: Buy a "smart router" with time-based parental controls (lets you use the internet at night).
Nerd way to do this: Pihole with a script that enables and disables certain blocklists at certain times (free and open source, because fuck "smart" products)
This is why we trust but verify. Thanks mom for teaching me that cruel lesson of unplugging the phone cord to get me to bed (dial up days). It lasted about a week before I caught on you always came up from the basement before bed.
I'm so glad you never noticed I swapped my line with the guest bedroom. Also glad that ancient block in the basement could be hand wired.
"Yep, all night. Cleaned the spark plugs in my car and drained the blinker fluid. Couldn't have done it without him "
But instead it's "parent code"
"Yeah fortnight is closed. They close it so everyone can get a good night's sleep and be ready for the morning!"
I was going to tell a personal story about telling my son McDonald's was closed when I was broke or in a hurry but it reminded me of another cute store.
My son broke his arm in a McDonald's once. Hyper extended his elbow. Got a couple pins.
Anyway a year or so later they completely remodeled that McDonald's.
We drove by the demolished building during the remodel and my son shouted "that's what you get for breaking my arm! Who's broken now!"
Just FYI that cleaning spark plugs is actually a thing. Not common but sometimes they can get 'fouled' from things like oil or incorrect air/fuel mixtures.
Depending on the engine and whether or not you use double iridium-platinum triple splitfire plugs, once you go through all the work of taking them out, no sense in putting the same ones back in.