The Hikvision Reconnecting.Error Code HCNetSDK.dll[91] occurs when there’s not enough power for the camera or when the Auto Change stream type is on. The easiest solution to solve the problem is to use a better PoE power supply and turn the auto change stream off. Read this article to find out more about this issue and how you can fix it.

1. The problem with power

When using PoE (Power Over Ethernet) to power the camera up, is necessary to follow the international standards such as the IEEE 802.3af and IEEE 802.3at to have enough power. Each one of these IEEE standards are designed to have a specific voltage (V) and power (W) for the cameras and you need to use the correct power supply to have your camera working properly without some type of error.

Some users and technicians have reported a problem with the message in the Hikvision iVMS-4200 monitoring software screen “Reconnecting.Error Code HCNetSDK.dll[91]” due to the lack of power to the camera. Make sure you’re using the correct PoE power supply or switch. Make sure your cameras are getting enough juice from the network.

2. The auto change stream type

The Hikvision IP camera or recorder (DVR NVR) generates specific types of video stream such as main stream and sub stream to send through the network. Those types of streams can vary according to the resolution, frame rate and compression (such as H.264, H.264+ and H.265) and when the camera changes the stream automatically that can cause some issues.

To prevent the Reconnecting.Error Code HCNetSDK.dll[91] error open the iVMS-4200 to change the parameters (see the picture below). Click Tools and then System Configuration.

Uncheck the Auto-change Stream Type option on the Image Menu.

This simple change should do the job, now just come back to the main screen and reload the cameras and the error should go away. All the cameras should show up correctly.

If for some reason the cameras are still not loading properly just restart the iVMS-4500, sometimes a simple restart can save the day

3. Other recommendations

If you follow the instructions above everything should work correctly, however, sometimes there are some details that can prevent your camera to work. Let’s go through a few extra tips to help you get rid of the problem.

– Infrastructure (cables)
If you are not using good quality cables the power or data can be compromised and your system can fail and sometimes even generate the same “Reconnecting.Error Code HCNetSDK.dll[91]” error. For IP camera is recommended to use cat5e or cat 6 UTP cables. Also, make sure the cable are from a good manufacturers. You also have to take the distance into consideration, the limitation for UTP cable for data transmission is 100m according to the international standard.

– Camera factory default reset
Sometimes a bad configuration or a corrupted configuration file can hold your camera in an error state, so it’s a good practice to reset the device to factory default and reconfigure it from scratch. Login into the camera, go to the Upgrade & Maintenance menu. Click the restore button (see the picture below). Read this article for more information regarding resetting a Hikvision IP camera/DVR/NVR.

After restoring the camera to factory default configure it manually (don’t import a file with the old configuration).

– Firmware upgrade
It’s important to keep all the devices with the last firmware to make sure everything works fine, so take a look at the manufacturer’s website to see if there’s a new firmware for your device. You can also go directly to your device menu and click the button to check for the last firmware available.