AVOlio wroteSonicWall Firewall.
Ia not sure who told you to get that, i cant assist you in this specific router/firewall
if it was a juniper, cisco , mikrotik even low end routers i would give you a step by step,for this model you need to do your research
all i can do is give you the general steps
1- establish a PPPoE connection
2- asign your subnet to an interface or even the pppoe interface depends on router, could even be a loopback
3- establish RIP protocol on the pppoe interface and make sure you have a neigbor connected
4- configure RIP to advertise your Subnet
5- asssign a static default route
6- DO NOT NAT traffic sourced fron the public IP just send it.
Ogero should straight up give residential users a Vlan with their public ip without bgp or rip not sure why they do that.