As I have said elsewhere, I am a carpenter. I have no business whatsoever telling anyone how to install security cameras or a home network. This is just how I have done it after watching many YouTube videos by people who don’t know either. My way may be wrong but it is working for me. Your mileage may vary.
We needed new security cameras. The old ones were, well, old, and resolution has improved dramatically over the past seven or eight years since we bought them. I watched a lot of YouTube videos (of course) and read a lot of articles weighing the pros and cons of each type and brand of camera and system.