Magento 2 Product Attributes – Getting Value from Product Attributes

I have custom attributes for my products. Some attributes are in text format and some are in select list. I want to print those attributes in my template.
Here is code I am using:
`

$attributes = $_product->getAttributes();
$attrSetID = $_product->getAttributeSetId();
$objectManager = \Magento\Framework\App\ObjectManager::getInstance();
$resource = $objectManager->get('Magento\Framework\App\ResourceConnection');
$connection = $resource->getConnection();
$sql = "select attribute_group_id from eav_attribute_group where attribute_group_name = 'Additional Attributes'  AND attribute_set_id=$attrSetID";
$data = $connection->fetchAll($sql);
$groupId = array_pop($data);
if ($groupId && $attributes) {
    foreach ($attributes as $attribute) {
        if ($attribute->isInGroup($attrSetID, $groupId['attribute_group_id'])) {
            if ($attribute->getFrontend()->getValue($_product) == 'No') {
                $attrCode = $attribute->getAttributeCode();
//              $atest = $_product->getResource()->getAttribute($attrCode)->getFrontend()->getValue($_product);
//              $options = $attribute->getSource()->getAllOptions();
            } else {
                echo  $attribute->getFrontendLabel() . ' : ' . $attribute->getFrontend()->getValue($_product) . '<br />';
            }
        }
    }                            
}

And my problem is that Magento print only attributes which are not select type. For attributes that are select type Magento print "No".

I tried to print selected value of attribute like this, but output is still "No".

1. $_product->getResource()->getAttribute($attrCode)->getFrontend()->getValue($_product);
2. $_product->getAttributeText('custom_attribute_code')

In google I found only couple solutions for Magento 1x, so if someone can help me, i would appreciate it.
Thank you.