mqtt connection failure – Headwind MDM Q&A

I have deployed my headwind MDM to a AWS EC2 and I have successfully tested enroll a device however I noticed in the logs I have these log “MQTT connection failure” and “Scheduling MQTT reconnection in 900 sec“. Also I followed the setup for the headwind mdm in the youtube tutorial

What I tried:

1.) I have already opened a port 31000 in the security group

2.)  in the /var/lib/tomcat8/conf/Catalina/localhost, it is correctly pointing in my EC2 and already restarted the tomcat

3.)  when I typed telnet mydomain.com 31000, I am getting “connection refused”

4.) I already confirmed I am not in Firewall and NAT

5.) I typed this command “sudo ss -tuln | grep 31000” in my EC2 server, it doesn’t give me any result or log anything

6.) I typed this command “sudo ufw status” in my EC2 server, it says “Status: inactive” so firewall is not currently active

7.) 

what should I do to solve my problem ?