I ordered a block of static IP addresses. How do I implement?

The Gateway's Public Dynamic IP does not change because you bought a Public Static block.  Your Public Static block is routed to your Gateway's Public Dynamic IP by the AT&T Network and when you put this information into the aforementioned page, your Gateway will know how to handle that traffic (that it will otherwise drop in the bit bucket).

Ignore Cascaded Router and setup Subnet Block using the CIDR provided as Public Gateway Address.  Set the range .65 through .69 for the DHCP but leave the primary DHCP pool set to Private.  This will cause the gateway to handle the public subnet on its LAN ports in addition to the Private IP space (typically 192.168.1.0/24) already there.  It will have the subnets router address (x9.xxx.2xx.70) on the LAN ports for this purpose and will send and receive appropriate traffic to x9.xxx.2xx.64/29 as well as 192.168.1.0/24.

You would statically set the WAN address of your router to be something between x9.xxx.2xx.65 and x9.xxx.2xx.69. (You could also do this via DHCP, but I'd discourage that), with a Default Gateway IP of x9.xxx.2xx.70 and the subnet mask provided (255.255.255.248).

Once you've done these things, reboot the Gateway and your router.  Then see if devices connected to your router appear to the Internet as coming from x9.xxx.2xx.6x as they should.

AT&T's official policy seems to be that they want to send a tech out to do it and include a $99 install fee in addition to the monthly charge in support of this.  Which is utterly stupid because 95% of techs know less about how to do this than you do and have to call up someone to walk them through it, but it's just "the way things are done™."

If you have the IP address, you can do it yourself.  To change your public facing address for up to 5 computers is easy.  If you want to do all of your computers, that's pretty easy too: you need a router behind your gateway and just assign it one of the 5 public addresses and connect all your devices to it.

Normally will be scheduled for a tech installation appointment with $99 charge added to next bill.

The tech will setup the gateway assignments and provide you with the assignments.

If the order has been completed and you haven't seen a technician come and configure your Gateway with the IP block for you, you have a problem.  You'll need to get AT&T Support to look up the IP block and tell you the starting address before you can use it.

Once you have the starting address of the block, you can configure the Gateway in one of two basic ways in the Home Networks > Subnets & DHCP page of your gateway: either the Public Subnet or the Cascaded Router must be turned on (not both) and configured for your block.  Which you use depends on how you want the IP address block to be handled/routed in your network.  

Do you have a router you want to manage the subnet block for you (Cascaded Router), or do you just want to assign the IPs to devices directly connected to the Gateway (Public Subnet)?

I want to change the public facing IP address.  Yes, I do have a cascaded router but the ip in the BGW320 has not been  changed.  So a tech will have to come out for that?

This is the info AT&T provided

(I masked out a lot of it for security).

CIDR: X9.xxx.2XX.64/29
Subnet Mask: 255.255.255.248
Gateway IP: X9.xxx.2XX.70
Starting IP: X9.xxx.2XX.65
Ending IP: X9.xxx.2XX.X9
Primary DNS: 68.94.156.1
Secondary DNS: 68.94.157.1

So yes I use a router behind the gateway.

But how does the gateway public ip get changed?

Seems to me that is what I am most interested in.

THANK YOU!

I think we are golden!

Thank you!

Man if I can push my luck....

1. Got my router configured static with the "new" ip address, network back up!
2. Got my VPN tunnels back working
3. When I go to what is my ip I do see the "new" ip address

So all of that is good.

But my other questions are:

• How should my IP passthrough settings look?  I do want to restrict that outward facing IP address to the router only.
• I don't have anything other than the router connected to the BGW320 but would I want to or no?  (anything else connected to it would not be in the network managed by the router right?)
• What would I (potentially) use the other four unused IP addresses for?
• If someone hits my former outward facing IP address, with that allow them to learn the new one?

How should my IP passthrough settings look?  I do want to restrict that outward facing IP address to the router only.

I wouldn't have any IP Passthrough in this configuration.  You don't want the traffic from the Public Dynamic to go anywhere, so let it be discarded at the Gateway's WAN.

I don't have anything other than the router connected to the BGW320 but would I want to or no? 

Probably not except for management or guests that you don't mind using the Public Dynamic and don't want inside your network.  (Or public hosts such as I mentioned below).

(anything else connected to it would not be in the network managed by the router right?)

It's a different subnet/routing domain.  You could get to it from the Gateway's LAN using the Public IP assigned to your router... assuming you allow the traffic through your router's firewall and have Port Forwarding rules to take that traffic somewhere [assuming that your router is doing NAT], but it'd be just like coming from the Internet.  Likewise, assuming that LAN IP range doesn't conflict with the Gateway's LAN IP range (which you shouldn't do), you can access resources out on the Gateway's LAN via their private IPs.  Or, if you have set up additional Public IP hosts, you can get to them, too.

What would I (potentially) use the other four unused IP addresses for?

Additional routers?  NAS systems?  Plex hosts?  Public Web Server?  Spares in case you want to change your IP up to 4 times?

If someone hits my former outward facing IP address, with that allow them to learn the new one?

No.  If your BGW is configured to respond to PING, then someone might learn the Public Dynamic by tracing to one of the Public Statics, but not the other way around.

You are just so much more knowledgeable about this than anyone I have communicated with that works at AT&T 

Thank you so much!

So if understand what Passthrough does is send the Public Dynamic through to whatever? 

Turning off the Passthrough won't prevent my new static IP from getting to my router (which of course is what I want).