Magento 2 : How to get current IP Address?

Try This\

use Magento\Framework\App\Action\Action;
use Magento\Framework\App\Action\Context;
use Magento\Framework\HTTP\PhpEnvironment\RemoteAddress;

class Index extends Action {
    private $remoteAddress;

    public function __construct(
        Context $context,
        RemoteAddress $remoteAddress
    ) {
        $this->remoteAddress = $remoteAddress;
        parent::__construct($context);
    }

    public function execute()
    {
        $ip = $this->remoteAddress->getRemoteAddress();
        echo "Visitor's IP = ".$ip;
    }
}

Source Source

Please try following

   if(!empty($_SERVER['HTTP_CLIENT_IP'])){
    //ip from share internet
    $ip = $_SERVER['HTTP_CLIENT_IP'];
}elseif(!empty($_SERVER['HTTP_X_FORWARDED_FOR'])){
    //ip pass from proxy
    $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
}else{
    $ip = $_SERVER['REMOTE_ADDR'];
}
return $ip;