Comcast Fiber with Sophos UTM

CCSNV used Ask the Experts™
I have a Sophos SG230 UTM device that I am wanting to use with Comcast FIber, my question is how to configure the WAN nic for use?

Here is what CC gave me:

Assign to your Layer 3 device:
P2P IP:  50.*.*.128/29
Gateway: 50.*.*.129
Customer Layer 50.*.*.130-50.*.*.134
P2P Subnet:
Customer’s Usables:
Customer Allocation: 50.*.*.0/27
Customer Useable IPs: 50.*.*.1 - 50.*.*.30
Customer Allocation Subnet:
Usable IPV6 Block – N/A
DNS Servers:
Primary:           Secondary:

So for the WAN address, would i assign the 50.*.*.130 with the 50.*.*.129 as the GW and then use the customer usables entered as secondary IP addresses then NAT the traffic, or would I assign the customer usable to the WAN directly and add the remaining as secondary?

Sorry, new at fiber setup and you help is appreciated.
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Distinguished Expert 2018

A key difference between the cable and fiber services is that Comcast makes you do your own routing with the fiber service.

That said, I would invest in a router or layer 3 switch. 2Makes life much easier. That device would be between your Sophos and the Comcast fiber unit.
"So for the WAN address, would i assign the 50.*.*.130 with the 50.*.*.129 as the GW"
thats correct.
you may use a private IP address-range at the customer lan and use NAT / masquerading at the external interface.
or you use the "customer usable " IP range at the LAN or DMZ and are free to use NAT also or not.
Distinguished Expert 2018

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