How to resolve the problem "Error! Network is not available" in android 9 and higher

It may due to the your website  that's not secure enough , to skip this problem please try this solution :

First open your androidmanifest.xml file and add this line of code inside the application tag

android:networkSecurityConfig="@xml/network_security_config"

like this example : 

<application    
android:name="com.domain.apps.appname.AppController"    
android:allowBackup="true"    
android:icon="@mipmap/ic_launcher"    
android:label="@string/app_name"    
android:theme="@style/AppTheme"    
android:largeHeap="true"    
android:supportsRtl="true"    
android:networkSecurityConfig="@xml/network_security_config"    
tools:replace="android:icon,android:theme">

Then go and create a new file in the XML folder , copy this content into this  file :

<?xml version="1.0" encoding="utf-8"?>
<network-security-config>    
<base-config cleartextTrafficPermitted="true">        
<trust-anchors>            
<certificates src="system" />        
</trust-anchors>    
</base-config>
</network-security-config>

Remove the app from your device and start to runing the app again from your android studio .

Good luck in your business.