title: Ads do not appear in some devices
body: <p>When I test the test ads appear on one phone while another phone does not appear even though they are both the same version of the system and even when I tried it on a higher version it did not work (although it is a test ad nothing more)</p>
  <p>Java code</p>
  <pre><code>Public class MainActivity extends AppCompatActivity {
  
  private AdView mAdView;
  
  @override
  protected void onCreate(Bundle 
  savedInstanceState) {
  
   super.onCreate(savedInstanceState);
   setContentView
  (R.layout.activity_main);
  
  MobileAds.initialize(this, new. OnInitializeationCompleteListener(){
  
   @Override
   public void 
   onInitializeationCompleteListener
   (Initial izationState initializationState){
  }
  });
  
  mAdView = findViewById(R.id.adView);
  AdRequest adRequest = new. 
  AdRequest.Builder().build();
  mAdView.loadAd(adRequest);
  
   }
  }
  </code></pre>
  <p>xml</p>
  <pre><code>&lt;LinearLayout
  xmlns:android=&quot;https://schemas.android.com/apk/res/android&quot;
  xmlns:tools=&quot;https://schemas.android.com/tools&quot;
  android:layout_width=&quot;match_parent&quot;
  android:layout_height=&quot;match_parent&quot;
  android:orientation=&quot;vertical&quot;
  tools:context=&quot;.MainActivity&quot;&gt;
  
  &lt;com.google.android.gms.ads.AdView
    xmlns:ads=&quot;https://schemas.android.com/apk/res-auto&quot;
  android:id=&quot;@+id/adView&quot;
  android:layout_width=&quot;wrap_content&quot;
  android:layout_height=&quot;wrap_content&quot;
  android:layout_gravity=&quot;center&quot;
  ads:adsSize=&quot;BANNER&quot;
  ads:adUnitId=&quot;ca-app-pub-3940256099942544/6300978111&quot;&gt;
  &lt;/com.google.android.gms.ads.AdView&gt;
  
  &lt;/LinearLayout&gt;
  </code></pre>
  <p>in gradel</p>
  <pre><code>dependencies {
  implementation'com.google.android.gms:play-services-ads:20.6.0'
  }
  </code></pre>
  <p>mainfest</p>
  <pre><code>uses-permission android:name=&quot;android.permission.INTERNET&quot; /&gt;
  </code></pre>