Zerotrust gateway dns filter

I want to filter content on our network. on guest wifi all the devices connected are BYOD and cannot install WARP. i added a dns location our network has a static IP. on the router i added the dns values shown on the instruction for the specific dns location save setting on router and restarted. I already created a firewall policy test to block youtube.com but when i test on the BYOD after restarting the site is not block . any ideas?