Hi John,
This is a symptom for authentication issues in MySQL servers.
Have you tried connecting to the same MySQL servers our MysQL Router using a MySQL client from this Windows machine where JBoss is running? If you don't have it available there you don't need to install the full server, just download the latest Server ZIP archive from
https://dev.mysql.com/downloads/mysql/, unzip it and you'll find the executable 'mysql.exe' inside of the directory "bin".
The other thing you can do is to connect to one of the servers and run this query:
"SELECT user, host FROM mysql.user;"
Note how the user in the error message is identified as "username@192.168.27.16". Assuming this is exactly what you are getting, you will need a user in each one of the servers that is able to match it, both in the user and the host part. The host part is usually expressed with wildcards, for example "127.%". If in the results from the query above you don't see the user 'username' with a host pattern that matches '192.168.27.16', for example, '%' or '192.%', then this user cannot authenticate.
If the user exists with a matching host, then you could be facing privileges issues. Please check the documentation in
https://dev.mysql.com/doc/refman/8.0/en/privilege-system.html for more details.
IHTH