Login failure or disconnection may:
1. The account or user name is incorrect
2. The account has been logged in on other devices
3. Too many incorrect login attempts
For the second possible explanation:
The system allows only one device to log in to the account. Logging in will force the logged-in device to log off.
For the third possible explanation:
The system allows 7 login attempts and locks for 30 minutes after reaching the value.
After 4 consecutive locks, the lock time reaches 24 hours.
After you have successfully logged in, all the attempts are cleared.