Have you asked your Internet provider to test your connection, but found no connection issues? One of the apps, on one of your devices (computers, smartphones, tablets, etc.), may be consuming all of your available Internet upload or download bandwidth.
If this is the case, you can try to narrow down which device is causing the trouble, then, on that device, narrow down which app (software program) is causing the trouble.
You can narrow down which device is causing the trouble by, one at a time, turning off connected devices, checking the Internet performance each time to see if things have improved. If you power off a device and immediately your Internet connection improves, and seems normal, then you may have found the problem device.
To determine the problematic app or program it may require contacting Support, or the device manufacturer, or the operating system vendor, to get instructions to view the Internet or Wi-Fi bandwidth usage statistics of each installed app on the device. If the usage statistics show especially high consumption for a single app, that app may be the cause of the trouble. Try disabling or uninstalling the app, or look for settings, in the app, to limit bandwidth usage (especially upload usage), and see if the trouble is resolved.
To view Wi-Fi usage on recent Android based devices:
- Open Settings ⚙ (On some devices, open the App drawer, then tap the Settings icon)
- Tap Data Usage
- Tap the Menu key (3 vertical dots, on some devices)
- Tap the “Show Wi-Fi” menu option
- Tap the Wi-Fi tab
- The Wi-Fi usage by apps will be displayed
To view network usage on Windows 10 devices:
Windows 10 users can use the Task Manager’s App history tab (Open Task Manager [Ctrl+Shift+Esc] > More details > App history) to view network usage of individual apps. Alternatively, there is a Data usage section in the Windows 10 Settings app (Start [Windows logo] > Settings ⚙ > Network & Internet > Data usage > Usage details).
Additionally, Windows 10 users should check this article with Advice for DSL Users with Windows 10 and Suddenly Slow Internet, to avoid slowdowns caused by sharing downloaded updates to other devices on the Internet.