Welcome to our Community Forum and thanks for posting.
Can I ask whether you always see this "low data mode" message or is it just in your home? Phones have such a setting to reduce WiFi and mobile data use such as turning off automatic updates, background tasks and photo syncing as examples. It's useful if you want to limit your usage.
On an Android Device, it Settings - Connections -Data Usage - Data Saver
On an IOS device, it's under Settings - Mobile Data - Mobile Data Options - Low Data Mode