After a successful login the record of your previously failed login attempts is deleted and thus reset, however, you should not be able to login once the login attempt limit is reached.
The devices can be removed in the same System -> Administration -> Access control section Security tab. An entry should be added in the List of login attempts if somebody tries to and fails to login.
Could you tell if you are trying to access the device from WAN or via a VPN?
Best regards,
Žygimantas