I run AdGuard as an addon to Home Assistant. If you want to stick to AdGuard you can go to Settings > Client Settings and set a per-client filtering rule. There is a tab in the client settings that can be used to filter specific services with a click. Setting an IP reservation for your child’s device in the DHCP settings of Unifi or your router will help ensure the IP address stays consistent.

For the PiHole option, you don’t actually have to let the PiHole handle DHCP. You just need to tell your DHCP server what DNS server to use. For example, my router is .1 and my Raspberry PI is .2. The DHCP server, my router, tells all devices .1 is the gateway and .2 is the DNS server. You may also need to set these settings on the individual devices to prevent them from ignoring your DNS settings, but that can be done from the network settings. Avast had some safe networking “feature” that would force my DNS settings to be ignored, same with my Android phone.

Of course, the downside to all of this is that any different device, different IP, device from a friend, or mobile data could bypass these restrictions. You may soon be in an arms race with your child and chances are they can get more clever that you can in a shorter time frame.

Best laugh I’ve had in a while. That is some grade-A jank.