Using the Reolink app, turn on HTTP in the doorbell. Once that's done you should be able to log into the DB's webGUI using a browser, give it a unique, static IP in the same subnet as the NVR's LAN but outside of your router's DHCP pool, enable ONVIF and RTSP in the DB, connect to the LAN and have the NVR look for its IP. The DB should NOT be connected to POE port of a POE NVR but to the NVR's LAN.