Thanks, all. Assigning IP addresses manually and connecting the PoE switch to the outside network connector on the NVR, which is configured in the same Class C subnet, brought everything online and working properly. Setting to H264 (not H264+, not H265) for the main stream was also required in...
Here's an update on this:
I procured an NVR with 16 PoE ports, a suitable PoE switch (unmanaged) and two IP cameras. I hooked up the two cameras directly to two PoE ports on the NVR and they work fine.
Next, I plugged the uplink port from the PoE switch into one of the PoE ports on the NVR...
A very basic question: Let's say there are six PoE cameras in another building all connected to a PoE switch located in that other building. Then there is a single ethernet cable between the PoE switch in that other building to the building where the NVR is located, and it is plugged into one of...