Moving wp-content to block storage volume

Because I’m running out of space, I’m trying to move my wp-content folder to a block storage volume. (from /var/www/html/ to /mnt/folder)

I tried creating a symlink from the wp-content to the new wp-content folder but that doesn’t seem to work. Then I tried using the following code in the wp-config file:

    //define('WP_CONTENT_DIR', '../../../../mnt/folder/wp-content');
    //define('WP_CONTENT_URL', 'https://site/wp-content');
    //define('WP_PLUGIN_DIR', '../../../../folder/content/plugins'); 
    //define('WP_PLUGIN_URL', 'https://site/wp-content/plugins');
    //define( 'PLUGINDIR', '../../../../mnt/folder/content/plugins');

It seemed to work, for the most part. But when I enable any plugins I get an MSQL warning saying there are too many connections. I get locked out of the admin dashboard but I can fix it by renaming the plugins folder(to disable the plugins). I found some information here: https://www.digitalocean.com/community/questions/how-can-i-connect-wordpress-media-library-to-one-or-multiple-block-storage-volumes

I’d really appreciate some help.