As far I know, this router do not have this function to schedule on wifi

Thanks for the info! Much appreciated.

If it is for only a few devices it is possible to use parental controls to stop some devices from accessing wifi. Find out the Mac address of the devices, and add them to parental control.

Yep. If you want to block the device completely, you can use access control under security.
If you want to setup a time schedule , you can use parental control, choose white list but leave key word blank, this will block the device during a period of time.

Any chance the feature of wifi schedule to be implemented on the Archer C1200 some day? Users may want to turn off wifi at night also for energy saving purpose, etc. and not only to prevent children to access the internet at night. This is a common feature for many basic routers, and I bought this one assuming that the wifi schedule would be implemented by default. Would be sad to just give up with this device and go for Netgear or others with the same level of prive AND the wifi schedule (not to mention Point access feature, proper MAC filtering and so on).