Multi server and remote mysql, how to set config.php and other configuration?

[basketmen]

I have two servers

- one local server in my country server1.domain.com, ip lets say 111.111.11.111, contained the files and mysql
- one in US server2.domain.com, ip lets say 222.222.222.222, contained only files, i planning the mysql remote to first server above

in includes/config.php i already changed

$config['MasterServer']['servername'] = 'localhost';

to be server1 ip

$config['MasterServer']['servername'] = '111.111.11.111';

i already try too

$config['MasterServer']['servername'] = 'server1.domain.com';

but the forum in server2 still cannot opened 111.111.11.111/~username, its only loading or cannot opened/time out, the forum in server1 is still normal can opened 222.222.222.222/~username

Nb 1. in server1's "Remote Database Access Hosts" in cpanel i already add server2's ip or server2.domain.com, that are able to access database

Nb 2. i already try before add the mysql in server2.domain.com too, and using localhost, the forum running normal in server2, so the problem now i want to connect it to server1.domain.com mysql with remote

please help guys what i am missed or how to make mysql working using remote in two server2