MQTT Disconected using AWS IoT core

Hi everybody!!

I'm using IoT core from AWS to receive data with MQTT at NodeRed. However, my MQTT nodes just keep disconnected every time I activate my certificates from AWS IoT Core.

The first time I've created the mqtt nodes, they worked. But later they keep disconnected. I look into my AWS thing, certificates, policy, and testing them on the AWS page and they work normally. The problem might be at NodeRed.

I just found that if I uncheck the "MQTT node" => "Edid server" => "Use clean session" it turns connected.
What do these options work for?
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