I used 10.0.2.2 successfully on my home machine, but at work, it did not work. After hours of fooling around, I created a new emulator instance using the Android Virtual Device (AVD) manager, and finally the 10.0.2.2 worked.
Inside the emulated Android, go to Settings > WiFi, check if it is connected to AndroidWiFi hotspot (which represents your host computer), and then click on Advanced at the bottom, then check the Gateway address: it should point to 10.0.2.2 . If not, then you have another issue, maybe changing proxy settings can fix your issue, see here how to do that with Android Studio since 2022, as the proxy setting is now hidden away: How to configure proxy in emulators in new versions of Android Studio?
In case your web app can be accessed from your host computer, but not inside the emulator, the root cause can be that your local server is restricting access to some interfaces for some reason, likely for security reasons.
Then, try to access this simple server from your emulator's Chrome browser, eg, :8000. If it works, then this confirms that your local server is restricting access to some interfaces. You need to read your local server's documentation to broaden permissions.
Now, your web app should be accessible from inside the emulator, using Chrome app, with the URL :. The last piece of the puzzle is to add permissions in your Android app to access 10.0.2.2 and especially cleartext if your local webserver is not equipped with a SSL certificate (the most likely scenario for a local development webserver - just check if : works or only : from the host computer). This will allow your Android app to access your local webserver, just like Chrome does.
This tutorial only covers the issue of accessing/reaching a local webserver on the host computer from inside an Android emulator, but once this is fixed, the webapp may remain dysfunctional, even if reachable. One example is to experience an infinite loading loop. To debug further issues once reachability is resolved, you can use chrome://inspect in the Chrome Browser to attach to the Android WebView inside the Android emulator and live debug it as if it was rendered on your computer.
Only then, configure a reverse proxy on the bridge of the Android emulator that will forward localhost HTTP requests to the appropriate port (e.g. 8000) of the localhost server running on your host computer and vice versa:
The list is organized by guest operating system (the system being emulated), grouped by word length. Each section contains a list of emulators capable of emulating the specified guest, details of the range of guest systems able to be emulated, and the required host environment and licensing.
While the ARM processor in the Acorn Archimedes is a 32-bit chip, it only had 26-bit addressing making an ARM/Archimedes emulator, such as Aemulor or others below, necessary for 26-bit compatibility, for later ARM processors have mostly dropped it.