Message from SQL Server: SQLSTATE[HY000]

Hallo,
leider bekomme ich regelmäßig Fehler im meinen Logs zu sehen. Ich habe Debian mit Apache, PHP und MariaDB laufen und kann mir den Fehler hier nicht erklären.

Apache Logs:
[Wed May 26 16:30:45.928037 2021] [php7:error] [pid 15778] [client xxx.xxx.xxx.112:28283] PHP Fatal error: Uncaught RuntimeException: Could not connect to database. Message from SQL Server: SQLSTATE[HY000] [2002] Connection refused in /var/www/example.com/engine/Shopware/Components/DependencyInjection/Bridge/Db.php:91\nStack trace:\n#0 /var/www/example.com/engine/Shopware/Kernel.php(236): Shopware\Components\DependencyInjection\Bridge\Db::createPDO(Array)\n#1 /var/www/example.com/engine/Shopware/Components/HttpCache/AppCache.php(255): Shopware\Kernel->boot()\n#2 /var/www/example.com/vendor/symfony/http-kernel/HttpCache/HttpCache.php(238): Shopware\Components\HttpCache\AppCache->forward(Object(Symfony\Component\HttpFoundation\Request), true)\n#3 /var/www/example.com/engine/Shopware/Components/HttpCache/AppCache.php(106): Symfony\Component\HttpKernel\HttpCache\HttpCache->pass(Object(Symfony\Component\HttpFoundation\Request), true)\n#4 /var/www/example.com/shopware.php(122): Shopware\Components\HttpCache\AppCache->handle(Object(Symfony\Component\HttpFoundation\Request))\n#5 {main}\n thrown in /var/www/example.com/engine/Shopware/Components/DependencyInjection/Bridge/Db.php on line 91, referer: https://example.com/ozonisiertes-kokosoel
[Wed May 26 16:30:46.407261 2021] [php7:error] [pid 15777] [client xxx.xxx.xxx.112:28281] PHP Fatal error: Uncaught RuntimeException: Could not connect to database. Message from SQL Server: SQLSTATE[HY000] [2002] Connection refused in /var/www/example.com/engine/Shopware/Components/DependencyInjection/Bridge/Db.php:91\nStack trace:\n#0 /var/www/example.com/engine/Shopware/Kernel.php(236): Shopware\Components\DependencyInjection\Bridge\Db::createPDO(Array)\n#1 /var/www/example.com/engine/Shopware/Components/HttpCache/AppCache.php(255): Shopware\Kernel->boot()\n#2 /var/www/example.com/vendor/symfony/http-kernel/HttpCache/HttpCache.php(426): Shopware\Components\HttpCache\AppCache->forward(Object(Symfony\Component\HttpFoundation\Request), true)\n#3 /var/www/example.com/vendor/symfony/http-kernel/HttpCache/HttpCache.php(317): Symfony\Component\HttpKernel\HttpCache\HttpCache->fetch(Object(Symfony\Component\HttpFoundation\Request), true)\n#4 /var/www/example.com/engine/Shopware/Components/HttpCache/AppCache.php(188): Symfony\Component\HttpKernel\HttpCache\HttpCache->lookup(Object(Symfony\Component in /var/www/example.com/engine/Shopware/Components/DependencyInjection/Bridge/Db.php on line 91, referer: https://example.com/ozonisiertes-kokosoel
[Wed May 26 16:33:40.086089 2021] [core:notice] [pid 15770] AH00052: child pid 15774 exit signal Segmentation fault (11)
[Wed May 26 16:33:40.086242 2021] [mpm_prefork:notice] [pid 15770] AH00169: caught SIGTERM, shutting down
[Wed May 26 16:33:40.204627 2021] [mpm_prefork:notice] [pid 16408] AH00163: Apache/2.4.38 (Debian) OpenSSL/1.1.1d configured – resuming normal operations

MySQL Logs:
2021-05-26 16:33:40 242 [Warning] Aborted connection 242 to db: ‚shopware‘ user: ‚shopware‘ host: ‚localhost‘ (Got an error reading communication packets)

2021-05-26 16:33:40 241 [Warning] Aborted connection 241 to db: 'shopware' user: 'shopware' host: 'localhost' (Got an error reading communication packets)

Konfigurationen:

Custom PHP Config:
upload_max_filesize = 256M
post_max_size = 256M
memory_limit = 512M
max_execution_time = 256
max_input_time = 256
opcache.max_accelerated_files = 100000
opcache.memory_consumption = 128M
opcache.revalidate_freq = 5
opcache.fast_shutdown = 1
opcache.save_comments = 1
opcache.validate_root = 1
#cgi.fix_pathinfo = 0

Custom MySQL Config:

[mysqld]
group_concat_max_len=2048
innodb_buffer_pool_size=5G
query_cache_size=200M
max_allowed_packet=5G