I can't connect by mqtt

[Razormaid242]

Hello,
I'm very new and I'm trying to connect via mqtt to opendtu, but I can't connect, I always get the response disconnected from server. I have installed mosquitto and I have tested it and it works. To connect I use mqttexplorer, I understand that I only have to put the ip of the dtu the port and select the mqtt protocol, isn't it?
I have also modified mosquitto.conf with the right port and "allow_anonymous" true.
Another question, what port does the webapp use? to be able to connect from outside, for example from no-ip.org.

Thank you very much