I think the POS and the cameras/guest access should be separate networks but not really sure how to accomplish that.
You need to look into an access point. This will have segregation options for guest networks, allow more flexibility for changes and provide ease of management.
you SHOULD be separating your POS/internal networks from your guest network. If you aren’t please tell me the restaurant name so I can never go there.
the answer in your case is vlans.
to accomplish this easily, you may want to look into a small stack of gear from ubiquity or aruba. A router, switch, AP combo will get you what you need for a reasonable amount and provide service without the need for frequent upgrades.
both companies provide an easy “guest portal” feature but I really would not tackle this project if you don’t have the network chops.
this is really just the beginning and I hate to say it fundamental hurdle you will need to handle. The next would be throttling the guest network so some diner doesn’t max out your connection, with the next being content filtering so you aren’t hit month after month by ISP cease and desists for torrenting and other nasty things people try to lookup on public wifi.
Those are the basics. After that we dive deeper into shortening the DHCP lease time so you don’t hold allocations for more than say an hour. Or else you will deplete your IP pool after x amount of guests connect as you start picking up business.
After that you dive into more advanced mitigations.
Blocking the guest network from accessing the gateway login on 80/443/xxxx (whatever port the control panel listens on). Then we move on to cutting multicast traffic and blocking sharing protocols so you can protect yourself, and the customers from each other. From there you can implament a firewall rule to re-route DNS traffic to only poll your router so people arent accessing bad things by bypassing you and the list goes on.
But the basics should buy you time if you can atleast handle those so you can learn more about the equipment, customer base, and the industry as a whole to make more educated decisions.