Client is not authorised to connect because of TLS-SNI extension is disabled
Server Name Indication (SNI) is an extension to the Transport Layer Security (TLS) computer networking protocol by which a client indicates which hostname it is attempting to connect to at the start of the handshaking process. For HiveMQ cloud Free/starter packages, we require the TLS-SNI extension to be available and used With TLS-SNI enabled, the hostname is added to the “Client Hello” TLS packet, you can verify it by examining the packet as illustrated in this post.