db: ‘unconnected’

Hello,

When using hyperdb, we got a lot of

Oct  5 13:57:59 vMariaDB01 mariadbd[1770838]: 2022-10-05 13:57:59 3683932 [Warning] Aborted connection 3683932 to db: 'unconnected' user: 'unauthenticated' host: 'x.x.x.x' (Got an error reading communication packets)
Oct  5 13:57:59 vMariaDB01 mariadbd[1770838]: 2022-10-05 13:57:59 3683932 [Warning] Aborted connection 3683932 to db: 'unconnected' user: 'unauthenticated' host: 'x.x.x.x' (This connection closed normally without authentication)
Oct  5 13:58:00 vMariaDB01 mariadbd[1770838]: 2022-10-05 13:58:00 3683936 [Warning] Aborted connection 3683936 to db: 'unconnected' user: 'unauthenticated' host: 'x.x.x.x' (Got an error reading communication packets)
Oct  5 13:58:00 vMariaDB01 mariadbd[1770838]: 2022-10-05 13:58:00 3683936 [Warning] Aborted connection 3683936 to db: 'unconnected' user: 'unauthenticated' host: 'x.x.x.x' (This connection closed normally without authentication)
Oct  5 13:58:12 vMariaDB01 mariadbd[1770838]: 2022-10-05 13:58:12 3683974 [Warning] Aborted connection 3683974 to db: 'unconnected' user: 'unauthenticated' host: 'x.x.x.x' (Got an error reading communication packets)
Oct  5 13:58:12 vMariaDB01 mariadbd[1770838]: 2022-10-05 13:58:12 3683974 [Warning] Aborted connection 3683974 to db: 'unconnected' user: 'unauthenticated' host: 'x.x.x.x' (This connection closed normally without authentication)
Oct  5 13:58:12 vMariaDB01 mariadbd[1770838]: 2022-10-05 13:58:12 3683977 [Warning] Aborted connection 3683977 to db: 'unconnected' user: 'unauthenticated' host: 'x.x.x.x' (Got an error reading communication packets)
Oct  5 13:58:12 vMariaDB01 mariadbd[1770838]: 2022-10-05 13:58:12 3683977 [Warning] Aborted connection 3683977 to db: 'unconnected' user: 'unauthenticated' host: 'x.x.x.x' (This connection closed normally without authentication)

Using this config:

<?php
/**
 * Register the primary server to HyperDB
 */

$wpdb->add_database( array(
        'host'     => DB_HOST,
        'user'     => DB_USER,
        'password' => DB_PASSWORD,
        'name'     => DB_NAME,
        'write'    => 1, // primary server takes write queries
        'read'     => 1, // ... and read queries
) );

/**
 * Register replica database server if it's available in this environment
 */

$wpdb->add_database(array(
        'host'     => DB_HOST . ':' . '3307',
        'user'     => DB_USER,
        'password' => DB_PASSWORD,
        'name'     => DB_NAME,
        'write'    => 0, // replica doesn't take write queries
        'read'     => 1, // ... but it does take read queries
));

// That's it!

Maybe our config is missing something…