Hi,
When SAP Host Agent starts, the XDN listener Server (XDNLISTEN) is started automatically.
SAP Host Agent is started when CALL R3SAP400/SAPINIT is issued or automatically at IPL
when the QUSRWRK sub system is activated.
So, please try to use R3SAP400/SAPINIT command to call it directly as a workaround.
Please also refer to sap note 1257635.
Regards, Daniel
SAP on IBM i Team