I have a system with 10 IPC-HDBW4421EN 4MP cameras and 2 IPC-HDBW4800EN 4K cameras. I have tried with a Dahua NVR5216-16P-4KS2 and then returned it and now have a Dahua NVR4416-16P-4K. I do not like losing direct connections to my cameras so use an external PoE switch. Motion detection works...