Step 1, define a class Inherited from WebFormsFriendlyUrlResolver and override TrySetMobileMasterPage method, Code below is for your reference.
public class MyWebFormsFriendlyUrlResolver : Microsoft.AspNet.FriendlyUrls.Resolvers.WebFormsFriendlyUrlResolver
{
protected override bool TrySetMobileMasterPage(HttpContextBase httpContext, Page page, String mobileSuffix)
{
if (mobileSuffix == "Mobile")
{
return false;
}
else
{
return base.TrySetMobileMasterPage(httpContext, page, mobileSuffix);
}
}
}
Then update the RegisterRoutes method.
public static void RegisterRoutes(RouteCollection routes)
{
var settings = new FriendlyUrlSettings();
settings.AutoRedirectMode = RedirectMode.Permanent;
routes.EnableFriendlyUrls(settings, new MyWebFormsFriendlyUrlResolver());
}