Hello,

This is an error thrown from your Database for the DB user who is trying to connect.

I will do my best to help you resolve it.

You can connect the plugin to almost any MySQL, MSSQL, and PostgreSQL database using the Separate DB Connection section in wpDataTables, 

if you correctly input the details for the connection.

You first have to check if you have the following drivers installed, and activated.

These drivers need to be installed and activated on the server where your WordPress website is. 

After you install and activate those drivers, it should work.

If you're not sure how to install the drivers, please reach out to your hosting provider.

The server to which wpDataTables is connecting has its own method of establishing the connection, and we're using PHPs logic of connecting to separate connections.

 If there are errors your server returns, those are returned by the server, and only displayed by wpDataTables

 - there's no additional log within wpDataTables that would distinctively show you what's behind the error.

You can actually test the full features of our plugin, and test your remote DB connection on our Demo sandbox on this link,

if it is on a live server ( if it is localhost, then It can't be accessed by our Demo Site).

Then, when you have these installed, you need to contact the support of your remote Database server and ask them for instructions and details what is needed to be input in order to connect,

such as connection name, host, port, user, password, etc;

In the end, try to Test the DB Connection in our Plugin, and see if you get any errors.

If there are errors your server returns, those are returned by the server, 

and only displayed by wpDataTables -

 there is no additional log within wpDataTables that would distinctively show you what's behind the error.

If you are testing this on your own localHost server, which you configured yourself, then you can research for posts about the same error you are seeing online. 

There are a lot of other Posts with the same error, and it seems users managed to resolve this.

For example, please check this Page with a guide that shows some steps you can do, such as :

Check that the DB username, DB password, database host, and database port are correct, then insert them in the External DB connection details in our Plugin settings.

You can also check this StackOverflow Post, where a user managed to resolve this issue.

To summarize, you need to ensure that the DB user who you are using to connect has the necessarry privileges/access and if you are inserting all the correct details for your MySQL Connection, etc.

Try to connect via some other software first perhaps to check if it is letting your DB user connect with the same details, that can help to isolate the issue.

Or, in some cases, it is a good test to simply create a new DB user, make sure to set this user with full permissions, and then try if that new user connects ( to isolate if it is a permissions issue).

Let me know how it goes.

Thank you.