Despite multiple warnings and stern admonishment, DS continues his reckless behavior. I cannot possibly watch him every single second and DH is also WFH so cannot get very loud to stop him either as he won't stop without desperate measures. Not able to figure out how to restrict online games during school time. Please help!

block everything except what’s needed for school.
This, install super tight controls on all of his devices for school hours. Then give him some freedom after that.
I blocked all the known games, however he finds online games to play
@ Anonymous Can you set controls so that it only allows him to go to specific URLs only - during school hours, rather than blocking the never-ending list sites ? Not sure if its an option on the method you are using.
what does discord mean?
its a chat forum
Blocksite on Google Chrome. You can even set up a white list if he doesn't have too many unique address assignments.
somehow he figures out how to get around all controls.....I had painstakingly put in so many controls, but he factory re-sets his computer and takes off everything
Can you put on an admin password so he can't reset?
Clever little rugrat, isn’t he? So: whitelist only the school site. Everything else blocked. Administrator password required to do everything except turn it in and off. Put everything (all apps, everything) under a profile controlled by you. Put only what he needs for school in a profile that he has access to. This will have the effect of letting him sign on, but seeing nothing but his school apps and an internet browser that only goes to the school site.
and while you're at it, put a keystroke logger on there so that he gets used to the idea that nothing on the internet is private.