You could have the hub or router plugged into a smart plug which can be remotely switched on and off. I have a TP-Link HS100 Wi-Fi Smart Plug which I can turn on or off either by WiFi or internet for my CCTV cameras.
Would a wifi smart plug really be the best idea as a choice of smart plug for turning off the device providing the wifi?
If you go the route of using a smart plug you'd need to get some that does so via bluetooth so you don't lose the ability to turn the plug back on after you've turned it off. Without having to manually go to the plug and hit the button that is.
I'm thinking to turn it off when I'm at work so my kids don't spend all day playing on devices
Take em 5 seconds to get round that. Best bet is to unplug it and put it in your backpack and take it with you.
-------------------- Services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired 2 WiFi,) SH2 in modem mode with Airport Extreme Router. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.
Lol.... I used to have to do this 10 - 15 years ago when my kids were growing up. I did it via a scheduled firewall rule that blocked internet traffic for their devices/IP's. I have a VMB Hitron so can't comment on the hub3 etc.
It worked.... until 3G/4G came out and then I had to do a device amnesty at night otherwise they would be using the mobiles all night.