This bit of info might be useful to someone: Our iVMS-4200 software (V126.96.36.199) stopped showing the feeds from our NVR on just one PC. Most of the time it would show the error below. Now and then it would connect successfully. Reconnecting.Error Code HCNetSDK.dll.(Connecting to device failed. The device is offline or the network timed out.) In Device Management it was showing HCNetSDK.dll failed to receive data from the device. Re-installing the software (and lots of other things) didn't fix it! I managed to get around this by going to Tools, System Configuration and un-ticking "Enable Upgrading Device Automatically". That has fixed it!