Android Question MQTT unable to connect to hiveMQ cloud

Sub Process_Globals
    Private mqtt As MqttClient
    Private mytopic As String
    Private serializator As B4XSerializator
    Private serverURI As String = "tcp://192.168.1.15:1883" 
    Private user As String = "admin"
    Private pass As String = "Password"

'    Private serverURI As String = "ssl://adbeffbd072848c190f7afdad3301f45.s2.eu.hivemq.cloud:8883" 
'    Private user As String = "device"
'    Private pass As String = "password"

Sub Activity_Create(FirstTime As Boolean)
    If FirstTime Then
        mqtt.Initialize("mqtt", serverURI, Rnd(0, 999999999) & DateTime.Now)
        Dim mo As MqttConnectOptions
        mo.Initialize(user, pass)
        mqtt.Connect2(mo)
        mytopic = "update/memo" & mqtt.ClientId
    End If
    Activity.LoadLayout("1")
    Canvas1.Initialize(Activity)
End Sub

Sub mqtt_Connected (Success As Boolean)
    If Success = False Then 
        Log(LastException)    
        lblStatus.Text = "Errore connessione"
    Else
        lblStatus.Text = "Connesso"
        mqtt.Subscribe(mytopic, 0)
    End If
End Sub

    
End Sub