@Qubix 

Hey

How you do this depends on how you have your AP connected.. namely is it managed via a controller   OR   standalone?

If its Controller driven, you just need to create a second SSID and tick the box for GUEST NETWORK.   ticking this box will lock the network down to anyone on that SSID cannot see anything but the internet..  good for guests..   create a portal / password as needed and done.    Your AP will start to broadcast it in a few seconds.

If its standalone, choose WIRELESS and add a second SSID..   tick SSID ISOLATION to make it guest (same as controller)

In terms of using a seperate IP.   This would require a VLAN in place for the guest SSID, you would need an Omada Router and Switch to accomplish this..