These are the questions asked during IBM Db2 and system i monitoring training.
To connect to AS400/iSeries server from Applications Manager ensure that the ports mentioned under "Port Non-SSL" column in the link are not blocked in firewall. Also check out:
The user should be permitted to access QMPGDATA/QPFRDATA(used to collect disk details) and QGPL(used to collect problem details) libraries and permitted to execute the command CRTPFRDTA and DSPPRB.
Consider the following special authorities when you use an account of user class *USER such as *ALLOBJ, *SAVSYS , *JOBCTL, *SPLCTL to retrieve all data and perform AS400 admin actions from Applications Manager.