Sounds like a gaming issue for sure.
We have the kids electronics automatically lose wifi at 10pm. No more games after 9pm but they can watch Disney or Netflix. The Tornado is my night owl, she could be up until 4am easily if she had wifi. Heck she stayed up all night before long trips just so she can sleep in the truck easier. They don't have phones so no issue there after the wifi goes out. Luckily we homeschool so bedtime can be later for her.
Hopefully you can find some middle ground for Mini-B that works for everyone.