SQLSTATE[HY000] [2002] Connection refused

I’ve an App of a Docker Laravel installation that communicate with two Vue.js apps via mySql database. When I call the query from the frontend apps I get in console the following error:

{"errors":[{"message":"Internal server error","extensions":{"category":"internal"},"locations":[{"line":2,"column":3}],"path":["clients"]}],"extensions":{"lighthouse_subscriptions":{"version":2,"channel":null}}}

Checking the laravel.log on the DigitalOcean App I see this error:

[2022-11-19 08:12:40] production.ERROR: SQLSTATE[HY000] [2002] Connection refused (SQL: select * from `users` where `user_type` like CLIENT) {"exception":"[object] (Illuminate\\Database\\QueryException(code: 2002): SQLSTATE[HY000] [2002] Connection refused (SQL: select * from `users` where `user_type` like CLIENT) at /workspace/vendor/laravel/framework/src/Illuminate/Database/Connection.php:759)

My App settings has the App Spec variables like that

- key: DB_DATABASE
    scope: RUN_TIME
    value: xxxxx
  - key: DB_PORT
    scope: RUN_TIME
    value: "3306"
  - key: DB_HOST
    scope: RUN_TIME
    value: 127.0.0.1
  - key: DB_USERNAME
    scope: RUN_TIME
    value: xxxxxxx
  - key: DB_PASSWORD
    scope: RUN_TIME
    value: xxxxxxx

on the Laravel side, the config/database.php

'mysql' => [
            'driver' => 'mysql',
            'url' => env('DATABASE_URL'),
            'host' => env('DB_HOST', '127.0.0.1'),
            'port' => env('DB_PORT', '3306'),
            'database' => env('DB_DATABASE', 'xxxxxx'),
            'username' => env('DB_USERNAME', 'xxxxxx'),
            'password' => env('DB_PASSWORD', 'xxxxxx'),
            'unix_socket' => env('DB_SOCKET', ''),
            'charset' => 'utf8mb4',
            'collation' => 'utf8mb4_unicode_ci',
            'prefix' => '',
            'prefix_indexes' => true,
            'strict' => true,
            'engine' => null,
            'options' => extension_loaded('pdo_mysql') ? array_filter([
                PDO::MYSQL_ATTR_SSL_CA => env('MYSQL_ATTR_SSL_CA'),
            ]) : [],
        ],

on the Vue.js side

const apolloClient = new ApolloClient({
  link: ApolloLink.from([
    pusherLink,
    createUploadLink({
      uri: 'DigitalOcenAppURI/graphql',
    }),
  ]),
  cache,
});

I wonder where is the problem. Maybe mysql is not installed on the DigitalOcean app??

Thank you for the help