Our Community Forums will be closing on June 27, 2024. Please visit att.com/support for all your support needs.
Get superfast AT&T Fiber internet
H

New Member

 • 

4 Messages

Wednesday, June 23rd, 2021 10:48 PM

Cascade Instructions (LAN to WAN) for AT&T Fiber BGW320-505 To Second Router With Public Static IP Block

I'd like to cascade the BGW320 into my other router that's set up behind it, including managing a block of public static IPs I got. My understanding of what I'm trying to accomplish is to make the BGW320 as hands-off as possible so that the UDMP can manage the firewall and all traffic. I can find instructions for IP passthrough and other bits and pieces of things I need to consider. But I think the public static IP block adds a layer of complication. I've read that I should NOT do IP Passthrough and instead do the cascading thing. Again, I'm not sure and nothing walks me through the entire process that I can follow. I'm new to this stuff and I'm hoping someone can dumb it down enough for me to understand.

Here's what my setup looks like right now:

AT&T Fiber Internet --> BGW320-505 --> Unifi Dream Machine Pro (UDMP) <-- All other devices

  • Nothing else is connected to the BGW320 aside from the UDMP (LAN to WAN). That is, an RJ-45 cable is plugged into one of the BGW320's ethernet ports, and the other end is plugged into the "internet" port of the UDMP.
  • The only adjustments I made so far is to disable the BGW320 wifi so as to not interfere with the UDMP wifi access points.
  • As mentioned, I bought a block of 5 usable static public IPs from AT&T. But I'm not sure how to utilize these. The info the AT&T tech provided looks like:
    • Gateway IP XX.XX.XX.206
    • Subnet Mask XXX.XXX.XXX.XXX
    • IP Range XX.XX.XX.201 --> XX.XX.XX.205

If your network is working fine why do you want to do any of this?

I'm going down this road because I was trying to set up a Plex server. I ran into a "double NAT" issue and nobody outside my home network can access my Plex server. I think the double NAT issue will be resolved by cascading the routers.

Why did you buy public static IPs?

Also because of the Plex server. I thought these were needed to facilitate connecting to the server and that one of these static IPs would be assigned to it. Clearly I'm confused about this. I got it in my head that the UDMP would get one of the public static IPs and then the Plex server gets another one? Or maybe I'm supposed to assign static public IPs to all three devices in question (BGW320, UDMP, Plex server)? I'm really not sure. Currently the Plex server is connected to the UDMP like any other device.

What is your Plex server?

I bought a Synology DS920+ NAS. It has a built in OS that can install Plex onto itself. Setting up the hardware was fairly easy. And like I said, devices within my network have no problems streaming from the Plex server right now. External connections -- say, a friend with the Plex app on their TV -- can see my Plex libraries on their side but cannot stream anything. Ultimately this is what I'm hoping to resolve.

Thanks in advance for any help offered. Let me know if there's any other info or screenshots or pictures I can provide. I'm outside my comfort zone here but am very excited to learn how to do all this.

ACE - Expert

 • 

35.9K Messages

2 years ago

To get to the BGW320's interface, you access it from the LAN side, the default address is typically 192.168.1.254.

New Member

 • 

3 Messages

2 years ago

I run plex on the pass-thru and it's fine for outside users.

New Member

 • 

3 Messages

2 years ago

Thanks @JefferMC - Prior to passthrough mode the static IP block seems to be what is active on the LAN side of the BGW320.  That is, a laptop plugged in directly gets a static IP block address, and the management portal responds to the (broadcast - 1) address in that block.  Once I enable passthrough (or I think when I get brave, it should really be cascade), I'll be setting the WAN side of my internal router to the broadband address, in place of the BFW320 (or so I thought).  That means the broadband-facing port of the internal router/gateway can't have a 192.168.1.x address, so how would it know how to route the address you mention to the BGW320?

ACE - Expert

 • 

35.9K Messages

2 years ago

Cascaded Router and IP Passthrough are two very different things:

IP Passthrough deals with the dynamic public address and how it is handled.

Cascaded Router deals with a Public Static block and how it is handled.  You can Cascaded Router to an IP Passthrough device by specifying the address 0.0.0.0 as the Cascaded Router local IP ( and the Gateway will substitute in the WAN address for the actual routing ).

The Gateway will ALWAYS maintain a private LAN network on its internal LAN ports/WLAN, this never goes away.  The Gateway will also dual-home with the router IP of the the Public Subnet on its internal LAN if you set up the Public Subnet fields (vs the Cascaded Router).  You can tell it to issue Public Addresses via DHCP on the Public Subnet section (Primary DHCP Pool = Public).  


If you, instead, set up Cascaded Router, it will set up routing from its private address (192.168.1.254) to the private IP of your Cascaded Router  (or the WAN address if you've turned on IP Passthrough) and your Cascaded Router should have the Public Subnet's router IP on its LAN and use 192.168.1.254 as its Default Gateway.  

New Member

 • 

1 Message

2 years ago

This "cascade" is nonsense. At&t has always been garbage on this. If you look up or even call their support on static IP you will get 10 different answers with at least 6 different calls. Within the modem, map the public IP to the mac device (firewall) that is hosting your static that you need public. This is basically performing a one to one NAT. They don't tell you that, it's not intuitive and they can't help you. It's a joke!

Not finding what you're looking for?
New to AT&T Community?
New to the AT&T Community? Start by visiting the Community How-To.
New to the AT&T Community?
Visit the Community How-To.