If one tries to lock down the ‘Admin Console Port’ during initalisation (e.g. by entering ‘-1’ in the field, replacing the 9090) - then the server will start up without erorr or further ado; BUT
actually only listen on port 9090 in plaintext
not listen on port 9091 in ssl
reflect the config in the Server Properties the other way round
Screenshot attached - note the URL and hte config.