I'm assuming your Wifi is properly encrypted and you don't plan to let the camera connect to it (ie. LAN only).
Can I create a separate sub network for this camera?
If your router supports it, sure. It's just the question if it makes sense from a rechability POV. Where are the people watching things with your camera?
- In the open internet? Go ahead and separate your computers from the camera, with only internet access is available to both.
- At your computers? Well, then you can't separate it, of course.
Should I create a separate sub network for this camera?
From security POV, yes. While proper HTTPS connections are not in danger, there are reasons like
- You have HTTP without S too
- Government-level attackers (total surveillance...) can get valid fake certificates
- Sometimes, HTTPS is not used properly and is not secure (enough)
- Your camera can do more than sniffing connections. Eg. actively attacking your computers with yet unknown 0day exploits.
- Why not?
Finally, outside of bits and bytes, remember it's a camera. It has a lens. And the real world is as interesting as the digital one.