How to set up a time to turn off guest wifi?

My kids all use our quest network. Is there any way to turn off the guest network without turning off the main wifi?  It seems like this should be something very easy to do but It has been nothing but frustration. 

 I can't believe we have to go through all this nonsense just to control when the internet is no longer available on the guest network.

All I am trying to do is stop them from staying up on school nights. Sure the parental controls to block things is important. I am not convinced it works 100%.  Shutting off the guest network that they use at night would be 100%