CAN'T BLOCK THROUGH 10.0.0.01

Why on earth can I not block through the portal? While I appreciate the "easy" button of turning the Parental Controls "on" or "off" through the XiFi profiles we should also have the ability to block specific websites. I have children at home on school computers that I cannot link to our Bark account so I have to rely on my router to block the distracting websites (YOUTUBE) during school hours. I have tried putting it in as keywords I have put in the address and still I am catching my oldest on YouTube instead of school. I am over it! Do I have to go buy my own router and turn in this one or will I run into the same problems? I am beyond frustrated.