Yellow 'Internet' Port? What's the difference!?


Feb 28, 2012
Hi All,

This may seem a silly question(s), but, getting ready to set up my own network, I wanted to know what the difference is between the 'yellow internet' port on the back of most routers (I will have the Netgear N900) and the other 4 Ethernet ports that are usually on the back of a router?

All manuals say that you need to plug the modem into that port.
Is it just a normal Ethernet port??? Or is there some difference and you do need to plug in something specific to that port?

The reason I ask is because I also have the Billion BiPAC 5200 ADSL2+ Modem/Router (with an ADSL connection to the house) and I was curious what the relationship is when I connect these two devices to create a hi-speed network with internet access.

As I understand the N900 is just a wireless router. Not an ADSL2+ modem.
The Billion 5200 is the Modem.
I need the Billion 5200 to provide the internet to the N900.

Why though then does the N900 have areas for you to put in ISP data in its setup!?
Don’t I set up all the ISP information in the Billion modem??? … But once that is done and connected to the internet, doesn’t it just spit out a normal network connection? Do I feed that into the special ‘yellow’ internet port on the N900 or into just a normal Ethernet port on the N900???

How does this then all work with the DHCP configuration.
Also, don’t I want the internet to be fed to the N900 and then for the N900 to distribute it to the network as it is faster etc?
I don’t really want the Billion 5200 to do anything but give me internet. I don’t want it to do anything else…

Sorry if this is a bit noob. I am just confused exactly what is happening and how having effectively two routers should be set up and how they talk to each other and what is done where and what should be done where.
I don’t want to set anything up that will cause a bottleneck to the access of internet across a gigabit network or over the high-speed wireless network.

If that makes sense.

Thank you for your time and help!



Aug 16, 2009
Hi there,

The 4 ethernet ports on a router form a switch, and the yellow port connects to the ISP. This yellow port's connection is "split" so to speak, to the 4 ethernet ports and any wireless devices connected.

usually the cable from the modem plugs into the yellow port, but the device you have is modem+router, so it too has 4 ethernet ports at the back.
N900 is a wireless router, correct.
The Billion 5200 is a modem and wired router rolled into one. (I'm guessing it must be wired only cuz you won't get a separate wireless router just for kicks...)

To go wireless, you need not setup the ISP data into the N900, and yes, once connected the modem will give a "normal" connection out.

You have a choice of connecting the modem to the N900, that is, modem to yellow port or modem to normal port. The difference is that if you connect modem to yellow port, the devices on the N900 will form a separate network, not visible to devices on the modem/router. Modem to normal port will give you a normal lan connection.

Just make sure to change the IP address of the N900 so its different from the modem/router depending on the type of connection you make.
If the default is > 192.168.0.x (for modem to normal port) or 192.168.x.1 (for modem to yellow port)

As for the DHCP, it will have to be configured on the modem/router and disabled on the N900.