Hello @AlvinA,
If you want to have a guest network then I suggest that you set up 2 SSIDs(Wifi Networks). One for the guest users in NAT mode and one for your private users in Bridge mode.
Having a guest only SSID allows you to keep guest(unsecured devices) separated with each other and also from the internal users as enabling a guest SSID allows users that connect to it, to only be able to access the Internet.
Any printers or devices that you trust should connect in the private SSID in bridge mode and by doing that, those devices will be able to communicate with each other and with the rest of you LAN(Local Area Network).
Let me know if that is clear or if you need more clarification! 🙂