Some cameras have a feature called "Illegal login lock". Basically what a camera does is, it locks itself after a certain number of incorrect login attempts to prevent brute force password cracking.
When this happens, the user cannot access the camera even with correct credentials for a predefined period. Sometimes this is 15 minutes sometimes a few hours.
In Admin Portal what sometimes can happen is the user will try to add the camera but will either forget to setup ONVIF user on the camera or will use the wrong password in the admin portal and because our platform does a few attempts to connect to the camera this usually leads to a camera "locking" itself and thus even after the user corrects the mistake the camera cannot be added until the "lock" is removed.
To remove this lock sometimes it is enough to reboot the camera in other instances only a full factory reset will speed up the process or users have to wait for the camera to unlock after the waiting period is over. The illegal Login Lock can be disabled on the camera in some cases in others don't.
In HikVision please follow the steps below to disable the illegal Login Lock.