Weird, does that happen every time you run it?
It looks like a network issue might have occurred but that doesn’t make much sense if you’re running against a local broker.
Another guess is maybe the broker isn’t fully started inside of the container yet. Just to test sleep for 30 seconds after solace.start() in AbstractPubSubPlusTestCase. It shouldn’t really take 30 seconds but that should be plenty of time to troubleshoot if that is the issue or not and you can shorten the time to see how long it really needs if so.