Run the following commands in sequence:

[root@localhost ~]# zstack-ctl config_ui --server-port 8888  #Change the UI port to 8888.
[root@localhost ~]# zstack-ctl config_ui --webhook-port 8888  #Change the webhook host port to 8888.
[root@localhost ~]# zstack-ctl stop_ui  #Stop the UI service.
[root@localhost ~]# zstack-ctl start_ui  #Start the UI service.