I have spent the better part of two hours, followed all instructions above and yet this feature 100% does not work. Could you please clarify how well it works at your end as I doubt it is working at all.
The only other option would have been to turn guest wifi on and off for the kids to use, but only option is to turn off all wifi as you cant turn off one and leave the other on. In todays times with kids fixed on there phones the battle is real. If i was TPG I would have put more thought into which router to use as these features are very important.