@stuartandfiona You can set schedules for Internet as a whole or for individual web sites, but there’s no “daily max time” allocation. Due to background activities generated by devices (either PC or smartphone), it is hard for the router account for active Internet usage with accuracy.
The recommended practice is to set up schedules (aka calendars) for Internet access. You can find more details here: https://www.pcwrt.com/2015/12/how-to-set-internet-access-time-limits-in-pcwrt/. When needed, you can temporarily turn off calendar restrictions by clicking the “Pause” button next to Calendars. After the extended time expires, calendar restrictions will be automatically restored.