Hello Mike

Thank you for your purchase.

For wpDataTables to successfully connect to separate databases, please make sure that you have these drivers installed and enabled on the server where your WordPress site is:

From your response, it seems that ODBC and sqlsrv is installed, but can you please check your info.php file, and see what the PDO section shows? If it's not the same as in the screenshot above, you'll need to install those drivers as well.

Alternately, you can provide me with the separate DB connection's credentials (in a PRIVATE response), so I can try connecting to it. If I'm able to connect to it, it's definitely the drivers causing the issue on your website.

Hi again Mike

I'm also on PHP 8.0, and these drivers do work for separate DB connections.

I'm not sure on which server you are, but there are different installation methods depending on the server. 

Following the instructions you linked: https://docs.microsoft.com/en-us/sql/connect/php/download-drivers-php-sql-server?view=sql-server-ver15 should work fine. You can also reach out to your hosting provider and ask them to install these drivers for PHP 8.0

Hi again Mike

I believe drivers for PHP7.4 would also work, so let's try these. These are commands for Apache:

sudo apt-get install php7.4-odbc
sudo phpenmod pdo_odbc
sudo apt-get install php7.4-mysql
sudo phpenmod pdo_mysql
sudo wget -qO- https://packages.microsoft.com/keys/microsoft.asc | sudo apt-key add -
sudo add-apt-repository "$(wget -qO- https://packages.microsoft.com/config/ubuntu/16.04/mssql-server-preview.list)"
sudo apt-get update
sudo apt-get install mssql-server -y
sudo apt-get install -y php7.4-pdo-dblib
sudo phpenmod pdo_dblib
sudo apt-get install php7.4-pgsql
sudo phpenmod pdo_pgsql
sudo apt-get install php7.4-sqlite
sudo phpenmod pdo_sqlite
sudo systemctl restart apache2

Sorry, Mike, I don't have instructions for that, as I never used a Windows server.

You can reach out to your hosting provider, they should know how these drivers are installed on the server.

Hi again Mike

Unfortunately, we're all using either Linux or Mac, so we didn't install these drivers on Windows servers.

You can take a look at these pages:

https://www.postgresql.org/download/windows/

https://www.php.net/manual/en/ref.pdo-dblib.php

https://docs.informatica.com/integration-cloud/cloud-data-integration-connectors/h2l/installing-the-jdbc-and-odbc-drivers-for-mysql-connector/installing-the-jdbc-and-odbc-drivers-for-mysql-connector/installing-mysql-odbc-driver/installing-mysql-odbc-driver-on-windows.html

https://docs.microsoft.com/en-us/sql/database-engine/install-windows/install-sql-server?view=sql-server-ver15

https://blog.devart.com/installing-odbc-driver-and-creating-data-source-on-windows.html