C211: see if a different connection can be opened for each user

[infotel4iarc]

The connection to the database is initialized when starting and seems to be intended to remain alive until the server is stopped. A local run with the server started seems to show that the connection is unique. Random problems may happen when several users use the same connection. https://db.apache.org/derby/docs/10.15/devguide/cdevconcepts23499.html