Using AirPort Express as Primary Router ?

Unfortunately, turning the wireless off is not going to make the Netgear router a modem.....which is what you need if you want the AirPort Express to function as the main router on the network.

Are you asking about a DSL or a cable connection? If it is DSL, things are going to get really complicated. Here are the basics of what must be done with a DSL connection:

1. The Netgear needs to be setup as a simple bridge mode modem only. Whether or not that is even possible is likely a question for the ISP if they provided the modem/router to you. If the ISP did not provide the Netgear to you, then you will need to check with Netgear support for answers. If you have the model number of the Netgear handy, we can try to perform some checks.

As I mentioned above, simply turning off the wireless will not make the Netgear a modem. it will still be a wired router in charge of your network, so nothing really changes if you turn off the wireless on the Netgear.

2. Even if it is possible to setup the Netgear as simple bridge mode modem, you will need to check with the ISP to make sure that they will support this type of configuration. Frankly, I think they will likely be a lot less than thrilled to help you with this, and you will need them to help, as this is not easy.

3. The AirPort Express will have to be reset back to factory default settings and then set up again. The other AirPorts can stay "as is". Part of the setup of the AirPort will require that you enter your PPPoE connection credentials using the Apple setup utility. This usually consists of a user name.....it might be your email address with the ISP....and a password that the ISP has provided, or you have selected, if you had that option.

Bottom line.....unless there is a critical need to run the AirPort Express as the main router, it would be far better to leave well enough alone. If you do have a DSL provider, and you are not happy with them, now might be the time to look at a cable provider. Most of them offer simple modems with their service, and the connection speed options will be far higher than DSL could ever hope to deliver.

Perhaps the real bottom line here is that It is much easier to set up the AirPort with a simple cable modem than it is a simple DSL modem.

Guest Network......that makes things even more complicated.....since all 3 AirPorts will now need to be reset and you will have to set each of them up again......unless you only want AirPort Express Base to provide a guest network signal.

Have you considered using the Netgear wireless as a guest network....and adding a Netgear repeater or extender if you need more coverage? That would be a much simpler approach.

If you can provide the model number of the Netgear modem/router, we'll try to do some checking from this end on the feasibility of converting this to a modem.

But, we would suggest that you check with your ISP first to make sure that they will support this type of setup....IF....it is even possible. Most ISPs do not want you making major changes on the device that they provide.