If a JNLP Session is active and the JNLP Port is disabled by setting "Manage Jenkins->Global Security->TCP port for JNLP agents." to 'Disable', the TCP session is maintained. Subsequent sessions no longer connect, but the active ones remain open.
If a JNLP Session is active and the JNLP Port is disabled by setting "Manage Jenkins->Global Security->TCP port for JNLP agents." to 'Disable', the TCP session is maintained. Subsequent sessions no longer connect, but the active ones remain open.
This is working as designed. We feel like it is natural for a server to continue processing open connections until they are closed even if you disable or change the listening port.