- Log into My BT
- Click BT Sport and follow the instructions
- When you use the app and when you want to watch BT Sport at www.btsport.com
You can only use the BT Mobile Sport app on Smartphones. You can't access it via the BT Sport online player, Chromecast, Airplay, or any other devices (such as connecting to the TV through a cable).
Try it from the website rather than the app to see if it makes a difference.