My IVMS-4200 has stopped displaying my cameras. This seemed to happen after a power failure, but I have no idea why. I seem to be logged in and I can still view my cameras in the local browser.
I assume that you are using the ivms4200 on a laptop, if so the stream needs the security code (6 digit that is in the cloud setup) to display the video. Perhaps, post the screenshot of the ivms screen as well as the device manager