DB Session Error Message

I deployed my application on production server. now i can see this error

Illuminate\Database\QueryException
SQLSTATE[HY000] [2002] Connection refused (SQL: select * from `sessions` where `id` = QlK0M3El8UsvfKZGKqfCn2Eh7QGVpqbLViDiAl1s limit 1)
https://xxxxx.com/login

all of db credentials are correct . don't know the reason.

env file

...

APP_NAME=Laravel
APP_ENV=local
APP_KEY=cxxxxxxxxxx
APP_DEBUG=true
APP_URL=https://xxxxxx.com/

LOG_CHANNEL=stack
LOG_LEVEL=debug

DB_CONNECTION=mysql
DB_HOST=localhost
DB_PORT=3306
DB_DATABASE=lms_samadhi
DB_USERNAME=root
DB_PASSWORD=xxxxxxxxx


ACTIVITY_LOGGER_DB_CONNECTION=mysql2
ACTIVITY_LOGGER_DB_DATABASE=xxxxxxxx


BROADCAST_DRIVER=log
CACHE_DRIVER=file
QUEUE_CONNECTION=sync
SESSION_DRIVER=database
SESSION_LIFETIME=120

REDIS_HOST=localhost
REDIS_PASSWORD=null
REDIS_PORT=6379

MAIL_MAILER=smtp
MAIL_HOST=smtp.mailtrap.io
MAIL_PORT=2525
MAIL_USERNAME=null
MAIL_PASSWORD=null
MAIL_ENCRYPTION=null
MAIL_FROM_ADDRESS=null
MAIL_FROM_NAME="${APP_NAME}"

AWS_ACCESS_KEY_ID=
AWS_SECRET_ACCESS_KEY=
AWS_DEFAULT_REGION=us-east-1
AWS_BUCKET=

PUSHER_APP_ID=
PUSHER_APP_KEY=
PUSHER_APP_SECRET=
PUSHER_APP_CLUSTER=mt1

MIX_PUSHER_APP_KEY="${PUSHER_APP_KEY}"
MIX_PUSHER_APP_CLUSTER="${PUSHER_APP_CLUSTER}"

config> database.php

    'connections' => [

        'sqlite' => [
            'driver' => 'sqlite',
            'url' => env('DATABASE_URL'),
            'database' => env('DB_DATABASE', database_path('database.sqlite')),
            'prefix' => '',
            'foreign_key_constraints' => env('DB_FOREIGN_KEYS', true),
        ],

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

        'mysql2' => [
            'driver' => 'mysql',
            'url' => env('DATABASE_URL'),
            'host' => env('DB_HOST', 'localhost'),
            'port' => env('DB_PORT', '3306'),
            'database' => env('ACTIVITY_LOGGER_DB_DATABASE', 'xxxxxxx'),
            'username' => env('DB_USERNAME', 'root'),
            'password' => env('DB_PASSWORD', 'xxxxxxx'),
            'unix_socket' => env('DB_SOCKET', ''),
            'charset' => 'utf8mb4',
            'collation' => 'utf8mb4_unicode_ci',
            'prefix' => '',
            'prefix_indexes' => true,
            'strict' => true,
            'engine' => 'innodb',
            'options' => extension_loaded('pdo_mysql') ? array_filter([
                PDO::MYSQL_ATTR_SSL_CA => env('MYSQL_ATTR_SSL_CA'),
            ]) : [],
        ],