The set-up is possible though, but the routes make zero sense.
@DemoNIck:
where:
for the WAN interface under pfSense:
General Settings:
IPv4 Configuration Type: Static IPv4
Static IPv4 Configuration: 10.0.0.254/24
IPv4 Upstream gateway: NONE
Reserved Networks/Block private networks and loopback addresses: NO
Block bogon networks: NO
Enter the ISP routers internal IP 10.0.0.1 as upstream gateway here.
@DemoNIck:
for the routing under pfSense:
System/Routing/Gateways/ADD:
Interface: WAN
Gateway: 10.0.0.1
Default Gateway: YES
The gateway is set automatically if you enter the IP in the WAN interface settings, as above.
@DemoNIck:
System/Routing/Static Routes/ADD
Destination Network: 192.168.254.0/24
Gateway: WAN
System/Routing/Static Routes/ADD
Destination Network: 10.0.0.0/24
Gateway: WAN
Why want you add routes for networks which are connected to pfSense directly? That's absurd.
@DemoNIck:
for the routing under my ISP's MODEM/ROUTER:
#route add -net 10.0.0.0/24 192.168.254.1
The same here.
On the IPS router forward the whole traffic to the pfSense WAN IP.