Maui app running on Android local device cannot connect to webapi running on localhost (works on emulator)

Make sure that your webservice is listening on all interfaces ie. 0.0.0.0

Assuming the Android device and the computer are on the same network.

Find out the hostname for your computer (or set up a static ip on your home router for your computer)

point your android app to https://hostname:port/ or https://yourip:port/

To get my .NET MAUI app running on a physical Android device to connect to a local web API, I did the following:

1. Use Your PC’s Local IP Address: Instead of using 10.0.2.2 (which works for the emulator), I used my PC’s actual local IP address. You can find it by running ipconfig in the command prompt. My API URL looked something like https://IP:7260.
2. Update launchSettings.json: I configured my API’s launchSettings.json to listen on that specific IP and port. This made sure the API was accessible from my Android device. Here’s a snippet:

. Allow HTTP/HTTPS Traffic: I ensured my Android app could communicate with my PC by configuring network_security_config.xml to allow traffic to this IP address.

 <?xml version="1.0" encoding="utf-8"?>
<network-security-config>
    <domain-config cleartextTrafficPermitted="true">
        <domain includeSubdomains="true">192.168.1.12</domain> <!-- Your PC's IP -->
        <domain includeSubdomains="true">localhost</domain>
    </domain-config>
</network-security-config>

Update AndroidManifest.xml:

<manifest xmlns:android="http://schemas.android.com/apk/res/android">
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:networkSecurityConfig="@xml/network_security_config"
        android:supportsRtl="true">
    </application>
    <uses-permission android:name="android.permission.INTERNET" />
</manifest>

Purpose of the ApiSettings Class: The ApiSettings class helps manage the API’s base URL based on the platform the app is running on.

public static class ApiSettings
{
    public static string ApiUrl = DeviceInfo.Platform == DevicePlatform.Android
        ? "https://192.168.1.12:7260"  // Use your local machine's IP address for Android devices
        : "https://localhost:7260";    // Use localhost for other platforms
}

The issue can sometimes be that the API is HTTPS. There are two solutions. The first is to convert the API to HTTP. The second is, as shown in the link below, to run the following command in .NET CLI:

dotnet dev-certs https --trust

After running the command, use the following code:

public static string BaseAddress = DeviceInfo.Platform == DevicePlatform.Android ? "https://10.0.2.2:yourPort" : "https://localhost:yourPort"; 
public static string yourUrl = $"{BaseAddress}/api/yourApiEndpoint";