Adjust sound volume of your Android device from any other device that has a web browser, Android or not.
Therefore this also includes non-Android devices (such as PC, Mac, iPhone and so on).
Both devices must be connected to the same local network (Wifi).
1. Install this app on the Android device you want to control sound volume remotely, and start the application. It will give you an address.
2. Then connect to that address from another device, Android or not, using its web browser, and start controlling sound volume remotely, easily. You may even add the address as a favourite so you can access it even quicker.
This app will remain free, without ads, and opensource. Source code is available on GitHub, click the "Visit Website" link in Developer section.