My kids just love the Internet. Love love love the internet, including all the dark corners where kids should really not wander... I never thought I'd be censoring my kids, but it's an absolute necessity in my house.
To that end, I bought a Netgear router that came with Circle Parental Controls. Circle takes over all the DNS traffic on your network and can block any websites you choose. For example, my younger kid has everything blocked except Minecraft. My older kid is allowed to use Amazon, but not Youtube. It can be a bit tricky to move beyond the built in rules, but Circle can block (or allow) any website based on the domain name. It's all controlled with the Circle app on my phone.
Whenever a new device joins the network, I get a notification from Circle and I can choose whether that device should be treated as a "kid" device or an "adult" device. Handy!
We just got one of these and are still very new to it. My husband has really been the one to manage it but nice to read your recommendations that is has been so helpful.