https://devzone.nordicsemi.com/f/nordic-q-a/123852/connect-to-azure-event-grid-using-ca-signed-certificatesHi, I&#39;m developing a device that needs to be able to securely connect to a MQTT Broker using certificates signed by a CA. In short, I already have that working when connecting to a self-hosted Mosquitto MQTT broker Where 1) The nrf9151dk generates a CSRen-USTelligent Community 13Thu, 21 Aug 2025 08:08:32 GMThttps://devzone.nordicsemi.com/thread/546304?ContentTypeID=1Thu, 21 Aug 2025 08:08:32 GMT137ad170-7792-4731-bb38-c0d22fbe4515:956205df-0b69-4e26-9ac4-eeb3973cf8b1Jonas Hansen<p>After some more messing around with it, I found the solution:<br /><br /><strong>In Azure Event Grid, Clients must always be registered.<br /></strong></p> <p>I had the assumption then when using CA Signed Certificates, the client didn&#39;t have to be registered. And therefor I assumed the issue was not having the right cert attributes, but CN is enough.<br /><br />So when using CA Signed Certificates, you&nbsp;still have to&nbsp;register the client identifier (CN) my case</p><div style="clear:both;"></div>