No suitable servers found (`serverSelectionTryOnce` set): [Failed to resolve 'mongo']

#0 /var/www/html/core/models/MongoBase.php(118): MongoDB\Driver\Manager->executeQuery('news.source', Object(MongoDB\Driver\Query))
#1 /var/www/html/core/models/MongoBase.php(98): Mix\Core\Models\MongoBase::findItem(Array)
#2 /var/www/html/app/controllers/IndexController.php(26): Mix\Core\Models\MongoBase::findById(Object(MongoDB\BSON\ObjectID))
#3 [internal function]: Mix\App\Controllers\IndexController->stateItemAction('594eaf8cbc30b60...')
#4 [internal function]: Phalcon\Dispatcher->callActionMethod(Object(Mix\App\Controllers\IndexController), 'stateItemAction', Array)
#5 [internal function]: Phalcon\Dispatcher->_dispatch()
#6 [internal function]: Phalcon\Dispatcher->dispatch()
#7 /var/www/html/public/index.php(61): Phalcon\Mvc\Application->handle()
#8 {main}