@Mikejd 

The VR400 does have a guest network either located in the basic menu of the router or in the Advanced menu. There is not a schedule to control only the guest network, but for the entire router. You can find that in the Advanced > Wireless > Wireless Schedule menu.

@Tony 

Thanks for this. I have tried to set up a guest network but I really need it to be on a separate time schedule to the main network. So unfortunately this won't work for me. I am looking for an alternative solution.

@Mikejd 

One inexpensive option is to get an Extender such as the RE220, use a different SSID and it has time controls. 

If you are considering a TP Link extender (or router), you can select the model, go to the support page and select the emulator to see what controls it has.

For example: https://emulator.tp-link.com/RE220v2/index.html

@ArcherC8 

Thanks for your suggestion. I have ordered one of these.

I tried the emulator and I think I can see how to set it up. I am assuming that the extender connects to the main WiFi so will be subject to any time controls there. I then set up any additional control on the extender. The main WiFi would be available from 7a.m. to 10p.m.; the extender would then be further restricted between 11a.m. and 5p.m. The kids will login to the extender and any one else could continue to use the main network, I just need to set appropriate passwords.

Does that sound feasible?