Shelly Plug: how to use MQTT with TLS connection

[mice777]

I use MQTT server with ports 1883 and 8883, with self-signed certificate. Tested with other clients, both connections work.

However, I can't make Shelly PlugS to connect over TLS. It works with non-SSL connection.

I set connection type to "User TLS", and disable "Use client cert..." option:

 

Under TLS Configuration settings, I upload PEM file with certificate used by the server:

The pem file is in format:

-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----

I don't upload other 2 certificates (Custom client certificate and Custom client key) because I disabled client identification.

 

I restart the device, and watch logs:

Shelly:

shos_mqtt_conn.c:623 MQTT0: Connecting to 192.168.1.40 (192.168.1.40:8883) SSL
shos_mqtt_conn.c:512 MQTT0: Connect status 256
shos_mqtt_conn.c:885 MQTT0: Connecting after 55117 ms

Server log:

2024-08-12 01:57:37,993 TRACE - Client with IP '192.168.1.231' sent SNI hostname '192.168.1.40'
2024-08-12 01:57:38,024 TRACE - Client null disconnected ungracefully.

So the result is that Shelly can't connect to my mqtt server over SSL.

Can someone explain me how is this supposed to work?

 

[mice777]

Well, I made it work, but using standard server certificate. I didn't need to use user TLS.

Problem was that Shelly failed to connect to HiveMQ broker, but I replaced it by Mosquitto, since then TLS connections work as expected.