Could it be that there are other security settings except username and password?
Mysql uses a security concept which takes the IP address in account as I explained above. If you want to test the mysql connection, use the mysql command and for the test you have to run it on the salve and not on the amster or any other server.
So to test the connection, login on the shell of the slave server and issue this command:
mysql -h master.server.tld -u root -p
replace master.server.tld with the hostname of your master server.
Another important thing is that you edited the /etc/hosts files eaxctly as described in the installation instructions on all servers that belong to the clusetr. E.g.
is ok while:
18.104.22.168. sv1.server.tld sv1
may cause the mysql connect to fail.