Unexplained disconnect, with mysterious error message

Occasionally we have clients time out, and following the timeout debug message is this mysterious ooutput:

connection in user state {32}

This only shows up in these unexplained and seemingly random disconnects.

I've searched the docs, online, and the HLAPI source code, but the only shred of information I found was a post similar to this one with no replies:

https://forum.unity.com/threads/connection-in-user-state-32.468795/

Since this disconnection appears random (and only seems to affect 1 client a time), there isn't a lot to go on. Finding out what this error message means might be a good clue.

Someone has to know where this comes from!