On the website, you are using a plugin with a CMS like WordPress, Joomla, or Drupal to create a mobile version of your website, then you need to check the details of the plugin to see if redirection for mobile devices is built-in. You may also want to look into using a different plugin that provides redirection. There are so many methods to redirect websites to mobile without plugins like:-
Javascript Mobile Device Detection
Detect mobile browsers by using Javascript for the screen width. The mobile devices will not have a screen width wider than a certain pixel size (e.g. 700 or 800). Users with screen width less than what you specify will be redirected to the mobile site. Here's an example of the Javascript you would want to insert into each of your pages:
<script type="text/javascript">
<!--
if (screen.width <= 700) {
window.location = " http://m.yourdomain.com ";
}
//-->
</script>
Using MIME Types in .htaccess to Detect Mobile Browsers
Another method for detecting and redirecting mobile users is to check for MIME types accepted by the user's browser in your .htaccess file. Those MIME types are used to determine if the visitor is using a mobile device and then a redirect is used to take those users to the mobile version of your site. Below is an example code that can be put into your .htaccess file to detect and then redirect mobile users:
RewriteEngine On
# Check for mime types commonly accepted by mobile devices
RewriteCond %{HTTP_ACCEPT} "text\/vnd\.wap\.wml|application\/vnd\.wap\.xhtml\+xml" [NC]
RewriteCond %{REQUEST_URI} ^/$
RewriteRule ^ http://m.yourdomain.com%{REQUEST_URI} ( http://m.yourdomain.com%{REQUEST_URI}) [R,L]
Tags
Add a rel="alternate" tag on the desktop page that points to the corresponding mobile URL. Add a rel="canonical" tag on the mobile page that points to the corresponding desktop URL. This allows Google's crawlers to understand the relationship between the two URLs – desktop and mobile
