Kudos to Gary and Jimel at Speco! They were very helpful on this...So with at least the N16NRN NVR with cameras connected to its internal switch, the URL for viewing Cameras is:
rtsp://admin:<password>@192.168.1.140:554/chID=X&streamType=sub
Where <password> is your password, although we ended up using an md5 encryptor for this...
and where X is the camera channel # (1-16 in this case)
The final issue was to get the Sub-stream changed from the default H.265 to H.264. This is unintuitively found in Settings/Network/Stream Settings/Substream settings
This seems to resolve the issue... (we'll see!? HaHa...)
