How to NAT behind a single public IP (DIA) without 2nd router?

[ciarlill]

I just had a DIA circuit installed at my home and I was given a block of 5 public IP addresses. Currently I have everything working but the router's WAN IP is not one of the public block I was given and it does not properly geolocate me. I don't really _need_ these public IPs but ATT just provides them. At some point I may utilize them as I build out my network but currently I just want to NAT my basic consumer devices behind one of these public IPs with correct geolocation.

I tested out creating a new OPT1 interface which uses the public IPs and skips outbound NAT. This works fine for a single device plugged into the OPT1 interface. My issue is that it appears that I can only configure DHCP for the other 4 addresses in the range. I want to put my whole 192.168.1.x network behind one of these addresses. Is there a way to do this without introducing another downstream router?

Config notes:

WAN Gateway IP: 12.xxx.yyy.49
Router WAN IP: 12.xxx.yyy.50/30 (static IPv4 configuration)

OPT1 Static IPv4: 12.zzz.ooo.17/29

Firewall rule: WAN interface, source: 12.zzz.ooo.16/29 NO NAT

[Maurice]

You can add the additional addresses to the WAN interface using virtual IPs. Then, adjust your outbound NAT rule(s) to use the desired virtual IP.

Cheers
Maurice