A free app for Android, by Treconite Apps.
Traffic Monitor shows you the current 3G/4G and 5G network speed of your Android phone, and the usage of data, in real-time. It has a built-in speedometer allowing you to test upload, download, and ping speeds. After testing, the app will give you an assessment of the result.
If you are having trouble with a slow network, this app can also help you identify its cause. Traffic Monitor displays a coverage map showing the signal strength in different areas. This helps you find areas with excellent signals.
The app is easy to use and works on Android 5.0 and above.