First try to block  1. youtube.com 2. youtu.be 3. googlevideo.com 4. googleadservices.com     If this not working, check how is policy applied? its on specific vlan? what is target ?  Best solution is to block Youtube first on Content Filtering->Category Blocking , also URL Filtering below -> Blocked Url list   youtube.com googlevideo.com googleadservices.com   Then make more policy into Group Policy  to allow this cointent  in Allow list URL patterns (Override) for youtu.be; youtube.com; googlevideo.com I maybe need more contents to solve this... ... View more

Try to change in protocol Any instead of only UDP... ... View more

  Simply, just create Layer 3 firewall rule into group policy You use for mobile devices and deny UDP:   #policy    #protocol      #destination        #port Deny        UDP            youtube.com          80 Deny        UDP            youtube.com        443     Mobile application use UDP protocol instead of TCP   Goran ... View more