Good to know it's working for you Antonio and thank you for the kind words.
I was amused at your detective work to discover you were using our jobe2 server. It sounds like whoever installed the CodeRunner plugin didn't realise they should install a local jobe server. jobe2 is just a lightweight server for helping people to get up and running. It has a limit on submissions per hour so if you try to use it in a classroom context you'll likely find it intermittently blocks you (and everyone else on the planet!) for an hour or so when its traffic limit is reached. More information on setting up your own Jobe, including links to a video and also to a Docker image, are available here.
Best of luck with your ongoing use of CodeRunner.
Richard