I saw this error message in the WildFly's log
Caused by: java.sql.SQLException: null, message from server: "Host '127.0.0.1' is not allowed to connect to this MySQL server"
Can you connect to the database using the root user and run this command?
select User, Host from mysql.user;
It will show the users and the hosts of the database. Is the user you are using allowed to use 127.0.0.1?