mosquitto how to find ip of connection attempts

I have a container mosquitto broker on my LAN and have disabled everything I can think of trying to troubleshoot the source of failed connection attempts I can see in portainer but without success.

portainer container health output:
Connection error: Connection Refused: not authorised. Error: The connection was refused.

I need a way to find out the ip of the device trying to authenticate.

How can I find the ip of the device ?