First idea was to upgrade FDM server with more memory, from 4 to 8.
But during tests we may see that the speed the same. Probably FDM need more CPU cores for speed-up or divide power between servers (mono one one, mysql for second).
First one in apache2 has faster UI. When the second one running as nginx proxy pass to xsp4 app running in screen session.
Here we may try & test another variants
Each variants may increase money for monthly usage.