DS-7604NI-K1 does not connect to HIKVision cameras - message "Already connected"

[marlon24]

Hello, I have a Dahua DVR that has HIK HIKVision cameras connected via ONVIF. I bought a second DS-7604NI-K1 DVR, which is only for viewing the cameras. When I try to connect HIKVision cameras to it, it says "Already connected" – "The webcam is connected to another device." Please help me solve this problem.