Level 3: Gumshoe

Bridging CG3100 to Billion 7800NXL


So I got myself a 7800NXL yesterday so I can stick it behind my bridged Telstra CG3100 cable modem. I did this due to the lack of functionality some functionality on the CG3100.

Anyway I've bridged the CG3100 by turning off wifi & un checking the NAT feature (which puts it into bridge mode)

Plugged the 7800 into port 4 from the CG3100
Logged into the 7800 went to quick connect
Choose Ethernet --> IP over Ethernet --> Obtain IP automatic

The 7800 than sits there for a while and eventually comes up with FAIL!!
If I plug my laptop directly to the CG3100 I get the public IP, DNS etc & it works

Am I missing something? It's driving me nuts!!!

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Level 16: Secret Agent

Re: Bridging CG3100 to Billion 7800NXL



Ok turn nat back on

disable dhcp on the 7800 and see if you can get the two to talk to each other and connect your laptop thru the 7800 to the Internet.


Also, what do you mean by "bridging" and what are you trying to achieve?


try that for starters...



Level 3: Gumshoe

Re: Bridging CG3100 to Billion 7800NXL

Hi Wanderer

I have the 3100 in bridge mode... so I can use the Billion to do all the router stuff.

The reason I want to set this up is because I need to use different DNS servers than Bigponds ones. I also need to add a static route into the router.
Neather of those 2 things can be done in the 3100 due to it's lack of functionality.

I'm begining to think there is something weird going on with the 3100 since I've setup routers like this before & never had a problem.

I wish I could get Telstra to either push new firmware to it or re flash.

It's pointless turning nat back on in the 3100 since that will than turn it back into the router and as such give me no option to setup the 2 things I listed above.

Level 16: Secret Agent

Re: Bridging CG3100 to Billion 7800NXL



Ok.. the first thing I would do is make sure that the two will work together in a standard config

I would make sure that RIP is enabled


now if there is a way to turn on some logfiles.. do so.


once I got them working ok.. I would start making small changes , checking the logfiles as i go and see what works and what doesn't


i would also assign the billion a static ip address on the 3100


the dns servers you could define on the laptop!


try and see if any of that works.. if not, I'll have to do some serious research...i like a challenge



Level 3: Gumshoe

Re: Bridging CG3100 to Billion 7800NXL

I have a Billion 8800AXL in bridge mode with a Motorola sb5101 cable modem.

I found the Billion QuickStart worse than useless. The manual is of no help.

I had no trouble bridging the SB5101 with a TP Link router.  I took down the settings and then applied them to the Billion.


These are my settings.


Go to Configuration

Set IP over Ethernet

Encapsulation Mode   LLC etc

Obtain an IP address automatically  Unchecked

WAN IP Address

WAN Subnet Mask

WAN gateway IP Address

Obtain DNS  Use Static DNS  

Primary DNS

Secondary DNS


I am in Queensland... your gateway and DNS servers may be different







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