Exception (Database Exception) 'yii\db\Exception' with message 'SQLSTATE[08006] [7] timeout expired'

in /opt/www/cms2/pr/vendor/yiisoft/yii2/db/Connection.php:320

Stack trace:
#0 /opt/www/cms2/pr/vendor/yiisoft/yii2/db/Connection.php(389): yii\db\Connection->open()
#1 /opt/www/cms2/pr/vendor/yiisoft/yii2/db/ActiveQuery.php(302): yii\db\Connection->createCommand('SELECT * FROM O...', Array)
#2 /opt/www/cms2/pr/vendor/yiisoft/yii2/db/ActiveQuery.php(271): yii\db\ActiveQuery->createCommandInternal(NULL)
#3 /opt/www/cms2/pr/vendor/yiisoft/yii2/db/ActiveQuery.php(227): yii\db\ActiveQuery->createCommand(NULL)
#4 /opt/www/cms2/pr/vendor/yiisoft/yii2/db/BaseActiveRecord.php(107): yii\db\ActiveQuery->one()
#5 /opt/www/cms2/pr/common/models/User.php(94): yii\db\BaseActiveRecord::find(Array)
#6 /opt/www/cms2/pr/common/models/LoginForm.php(69): common\models\User::findByUsername('aalekseev')
#7 /opt/www/cms2/pr/common/models/LoginForm.php(40): common\models\LoginForm->getUser()
#8 [internal function]: common\models\LoginForm->validatePassword('user_pass', NULL)
#9 /opt/www/cms2/pr/vendor/yiisoft/yii2/validators/InlineValidator.php(66): call_user_func(Array, 'user_pass', NULL)
#10 /opt/www/cms2/pr/vendor/yiisoft/yii2/validators/Validator.php(238): yii\validators\InlineValidator->validateAttribute(Object(common\models\LoginForm), 'user_pass')
#11 /opt/www/cms2/pr/vendor/yiisoft/yii2/base/Model.php(328): yii\validators\Validator->validateAttributes(Object(common\models\LoginForm), Array)
#12 /opt/www/cms2/pr/common/models/LoginForm.php(54): yii\base\Model->validate()
#13 /opt/www/cms2/pr/frontend/controllers/SiteController.php(119): common\models\LoginForm->login()
#14 [internal function]: frontend\controllers\SiteController->actionLogin()
#15 /opt/www/cms2/pr/vendor/yiisoft/yii2/base/InlineAction.php(54): call_user_func_array(Array, Array)
#16 /opt/www/cms2/pr/vendor/yiisoft/yii2/base/Controller.php(127): yii\base\InlineAction->runWithParams(Array)
#17 /opt/www/cms2/pr/vendor/yiisoft/yii2/base/Module.php(434): yii\base\Controller->runAction('login', Array)
#18 /opt/www/cms2/pr/vendor/yiisoft/yii2/web/Application.php(84): yii\base\Module->runAction('site/login', Array)
#19 /opt/www/cms2/pr/vendor/yiisoft/yii2/base/Application.php(339): yii\web\Application->handleRequest(Object(yii\web\Request))
#20 /opt/www/cms2/pr/frontend/web/index.php(25): yii\base\Application->run()
#21 {main}