Drop Doesn't

Can you try this instead with added logging?

 
 when HTTP_REQUEST { 
  
    log local0. "[IP::client_addr]:[TCP::client_port]: New [HTTP::method] request to [HTTP::host][HTTP::uri] with UA [HTTP::header User-Agent]" 
    switch -glob [string tolower [HTTP::header "User-Agent"]] { 
       "*torrent*" - 
       "*azureus*" - 
       "*windows-media-player*" - 
       "*microsoft-webdav-miniredir*" { 
          log local0. "[IP::client_addr]:[TCP::client_port]: Matched UA check. Closing TCP connection." 
          TCP::close 
       } 
       default { 
          log local0. "[IP::client_addr]:[TCP::client_port]: UA didn't check, redirecting." 
          HTTP::redirect http://targetsite.tld 
       } 
    } 
 } 
 

If TCP::close doesn't work, can you try reject instead? This should trigger LTM to send a RST packet to the client.

Can you post anonymized copies of the logs from both TCP::close and reject?

Thanks,

Aaron