MQTT multiple subscription

I am currently working on a project that involves subscribing to multiple topics using the MQTT protocol. However, I am encountering difficulties when attempting to subscribe to multiple topics using the same Ethernet (ETH) channel (in my project ETH_uni1). Currently, my project only functions when I have one subscriber and one publisher, each using a different ETH channel. I would greatly appreciate any advice or suggestions on how to achieve multiple topic subscriptions using the same ETH connection.

I am interested in learning more about TECO MQTT and its best practices for implementation. Could you please provide an example of an MQTT project (advanced project) that follows these best practices? Additionally, I would appreciate any advice or insights regarding the recommended practices for implementing MQTT. 

Thank you in advance for your assistance.