I've created a few profiles for my kids specifically to set up bedtime and off hours for devices in our home. I've noticed two different issues when devices are added to these profiles that have bedtime or off hours configured:

• Slow DNS routing to websites (speed test is fine and games play fine, but it takes a long time to find a website)
• Internet being blocked during hours where it should not be blocked (no clear pattern for why and when this happens)

I have:

• upgraded firmware
• subscribed to advanced parental controls
• confirmed I don't have time limits configured
• confirmed my time zone is configured properly and that I am definitely in hours where internet should be allowed (it happens in the middle of the day when it's not even close to being off hours)

Sometimes I just have to remove devices from the parental control profile to get them working again. When I remove devices from the profile, they immediately get back online and things seem to work fine. 

I do have a modem/router in the house from my ISP, but I've put our Deco router on that Modems DMZ host, so the firewall on that modem/router should be bypassed.