When this issue was a problem in our house, I would have them put their devices in my file cabinet and lock it. The devices were not allowed after 8pm and only after chores and homework were complete. I didn't set a time limit per se because they would work harder and faster if they knew they would get more playtime. Also learned to take the power cord from the playstation because my son knew he could still get on the internet this way. For punishment, I would lock up chargers on the weekend....they could have their devices but had to choose wisely how to use them. (They were not allowed to leave the house without at least 25% charge on their phones)Router upgrades are nice. We got one now that can be "paused" from my phone only. It is kind of funny to see them come running when the internet drops on them.