Right now, there is some basic controls available in the modem menu.
If you log into the modem, there is a parental controls area.
By device, you will have to narrow down which device is theirs (by MAC address).
Now the only issue is.. the way this one works.. its a block of time.. X to Y. But its per day. And it ends at midnight. So you could block out 11-midnight. but then for the next day, if you wanted midnight to 5am.. you would use up that days one, and not be able to block at night, etc.
They just had a BETA for a new app for some of the modems.. which hopefully would be out soon. Its supposed to have some controls from it.. but not sure if its just another way to set the SAME information (so the same limitations).
The settings inside these rogers modems, are on par with a cheap to mid range router.. they work, but dont have all the settings. To really get some more advanced settings and more control, you have to upgrade to your own 3rd party router to get them.