Splunk Regex - Works in regex101 but not Splunk

I've got a regex that's working in Regex101's editor, but when I paste it into Splunk I get garbage or no results: Regex: ^(?:[^ \n]* ){5}\[(?P\w+)(?:\].*\])(?P[^:]+) Sample entries: Oct 24 18:43:57 openvpn[36372]: 66.103.224.123:59349 [username] Peer Connection Initiated with [AF_INET]66.103.224.123:59349 Oct 24 18:28:54 openvpn[21337]: 66.103.224.123:50873 [username] Peer Connection Initiated with [AF_INET]66.103.224.123:50873 URL: https://regex101.com/r/by1mOW/7