You’ve used the wrong username and password
BT Home Hub 4 and 5 - Red Broadband Light
How to fix problem:
Reset your hub’s password by doing a factory reset.
1. Use a paperclip to press the factory reset button at the back of the hub for 20 few seconds
2. Wait five minutes for your hub's power light to turn blue, which means it’s reset
3. To reconnect to your devices find your wi-fi network name and password on the back of your hub, then on your device search for your network name and enter your password.