URL filtering network not working on ipad

[macchillsout]

I am trying to use the firewall on my router (ISP supplied not a airport) to filter a specific URL so that my child cannot go there. The settings are working on the computers on my network but the Ipad (wi-fi) with safari is opening pages on the URL that should be blocked on the router level. Any idea why the URL would not be properly filtered on the ipad? I just tried it on my iphone (on the wifi) and it also opened the page but I added a second filter for m.xxx and that seems to not block the iphone. Any idea what is going on with the ipad? Seems a router level block should be working.