Hi @Anz ,
Thank you for providing further information regarding your device. Supporting TLS is unfortunately not enough: In order to connect the HiveMQ Cloud (Free or PayG), the TLS SNI extension should be supported by the device and used.
The TLS SNI extension (Server Name Indication) adds a hostname to the ClientHello packet.
Can you confirm that your device does support the TLS SNI extension?
If you cannot confirm that by looking at the vendor’s documentation, you can check this empirically: use Wireshark and capture packets between your device and the broker. Please find the screenshot, which is illustrating where exactly to look, here: Client is not authorized to connect - #37 by simon_b
If the device does support the TLS SNI extension but does not use it, you will need to refer to the vendor’s documentation and find instructions on how to enable the TLS SNI extension there.
I hope this helps.
Kind regards,
Dasha from HiveMQ Team