Sort of - it's not exactly intuitive. Mumble's logs will look something like this:
2017-01-20 22:00 <71:(-1)> New connection: 123.123.123.123:56584
2017-01-20 22:00 <71:(-1)> Client version 1.2.9 (Win: 1.2.9)
2017-01-20 22:00 <71:JoeUser(42)> Authenticated
The first bit after the timestamp is in the format of <connection_id:username(user_id)>.
71 is the connection ID, with
(-1) and a blank username because at this point in time the user isn't authenticated yet. You'll note that on the first line, the IP address and source port of the TCP connection are logged.
Later, on line three, the user authenticates. We see the tag switch to username
JoeUser and user ID
42.
So what you need to do if you want to know what IP address someone joined from is to go through the logs and look for the username, look for the connection ID, then look from where that connection ID originally connected and you'll find the IP address.