" -s"> " -s"> " -s"> 
curl -k -m 5 --anyauth --user USER:PASSWORD "http://ROUTER_IP:49000/igdupnp/control/WANIPConn1" 
    -H "Content-Type: text/xml; charset="utf-8"" 
    -H "SoapAction:urn:schemas-upnp-org:service:WANIPConnection:1#ForceTermination" 
    -d "<?xml version='1.0' encoding='utf-8'?> <s:Envelope s:encodingStyle='<http://schemas.xmlsoap.org/soap/encoding/>' xmlns:s='<http://schemas.xmlsoap.org/soap/envelope/>'> <s:Body> <u:ForceTermination xmlns:u='urn:schemas-upnp-org:service:WANIPConnection:1' /> </s:Body> </s:Envelope>" 
    -s

(ROUTER_IP is the internal LAN IP of your router)

Source:

https://forum.sector3studios.com/index.php?threads/dedicated-server-api.10696/page-3#post-217524