Well.
I configured a TLS connection adding a CA to the broker, creating a client and uploading its certificate.
Then I can establish a TLS connection with the broker using the same port.
So, Solace cloud is using the same port for basic authentication and for TLS.
I don’t know why solace cloud is returning NON_AUTHORIZED when I use port 1883 for basic authentication.
In on premise version I can connect with basic authentication using the port 1883 without problems.
Anyway there is no problem for me to use ssl always. In fact, all my connections will use TLS.