I recently bought the Amcrest video doorbell (affiliate link) since I like my other Amcrest IP cameras, and I wanted a doorbell that was less cloud connected (the Amcrest doorbell requires an online account for the initial configuration but can be used completely offline at the expense of losing push notifications to answer the doorbell). The doorbell has the RTSP capability, so the video stream can be recorded based on motion events and/or 24/7 recording with video surveillance software like BlueIris or hardware such as the Amcrest NVRs (affiliate link).
Having an offline local network with no Internet access can be useful for a number of reasons. A few that come to mind are home lab networks, non-cloud IoT device networks, and “closed circuit” IP security camera network. For my network, I set up a separate offline IP security camera network using Amcrest IP cameras (affiliate link) as a baby monitor system. The quality is so much better and it is more secure than traditional baby monitors because I can lock down access from outside users.
After the long journey of learning more about IPv6 and how to enable it on my home network (see my page for detailed info), I discovered that I broke some functionality. When you have IPv6 enabled alongside IPv4 in a dual stack configuration, IPv6 will often take priority – after all, it is newest protocol intended to replace IPv4. I have created a network for my IP security cameras that is isolated from the Internet that I use as baby camera monitors.