Extend Netgear CG3100 Router network with Airport Express A1088
The problem with that model of AirPort Express is that it only supports 802.11b/g and not the much faster 802.11n. Using it with an Apple TV, I doubt you'll have sufficient bandwidth to watch HD content. If that's not a problem for you, then here is how I got my AirPort Express (A1264) to extend my TP-Link connection via Ethernet. I'm assuming you know your Netgear's IP and Subnet for the following.


Disconnect from your current WiFi network.
Plug in your AirPort Express and connect it via Ethernet to your Mac. If you don't have a Mac, make sure you have AirPort Utility on your Windows computer.
We want to start with a completely fresh configuration, so use a pen, paperclip, hair pin, whatever to hold in the little grey reset button until the light starts to rapidly flash amber.
Open AirPort Utility on your computer and select the AirPort Express Base Station, if it doesn't automatically open up the wizard. It may take up to a minute to show up so be patient. Make sure that you are scanning on Ethernet, too.
AirPort Utility should automatically assume you want to create a new network, so enter your existing SSID (the name of your network) that your Netgear router is using under "Network Name".
You can name the Base Station anything you would like, such as "My AirPort Express", or "Dopey" or "Batman", it really doesn't matter so long as it doesn't share a name with another device on your network.
Enter an access password to prevent unauthorised users from altering your settings and click "Next"
The AirPort Express will verify your settings and then probably ask you to cycle your modem's power. You can ignore this and just click "Next".
After resetting the Airport Express again, AirPort Utility should now show you your AirPort Express with a blinking amber alert and a few errors. Select it, and select "Edit".
Select the "Internet" tab and in the "Connect Using" dropdown, select "Static". This will allow us to specify the IP and Subnet that we want to use.
Set the IPv4 Address to something within your current network range (typically 192.168.1.xxx) If your Netgear router is 192.168.1.1, consider using 192.168.1.2, for example. Unless you have an atypical Subnet set, leave the subnet mask field, and fill in the Netgear's IP under "Router Address" and "DNS Servers".
Switch to the "Wireless" tab and confirm that the "Wireless Network Name" is correctly set to the SSID of the Netgear router. Change the "Wireless Security" drop-down to reflect the same security that your Netgear uses, and also type in your network password that you use to connect to the Netgear router.
Click "Wireless Options" at the bottom and set your Country. You can leave the Channel set to Automatic here, but if you would prefer, you can set the channel to whatever your Netgear is using, but offset by 3 either way (so if your Netgear uses Channel "2", set your AirPort Express to use "5"). Click Save.
Switch to the "Network" tab and set "Router Mode" to "Off (Bridge Mode)". This will allow all traffic to pass through the AirPort to the Netgear router.
Click "Update". You will be notified that the device will be temporarily unavailable. Click "Continue".
Disconnect the Ethernet cable from your computer and connect the AirPort Express to your Netgear router.


If everything went according to plan, you should be able to connect to your usual WiFi network and have the AirPort Express show up under AirPort Utility. From there, you should be able to connect your Apple TV without any problem. If it was connected to the Netgear network, it should automatically join the extended network anyway.