AirPort Is Node, How Do I Access The HD Through Ethernet (NOT wireless)?

You have already answered your own question.

The problem is that since the AirPort is configured to "connect to another network via wifi", it's NOT a DHCP server.....

And because the AirPort performs no routing functions when it is configured to join another network via WiFi......the Ethernet ports on the AirPort are not enabled at all.

In effect, the AirPort Time Capsule becomes a wireless hard drive in this type of setup....and nothing more.

You might want to consider a different type of setup for the AirPort, since your current configuration results in an undesireable "double hop" wireless situation, which doubles the amount of time for a backup to occur over wireless, and as a result doubles the chances of an error occurring during the process.

"Extend a wireless network" will work.....IF.....the AirPort Time Capsule is picking up a wireless signal from another Apple AirPort router. The Ethernet ports are also enabled in this type of setup.

"Create a wireless network" requires that you permanently connect from your main router to the AirPort using an Ethernet connection to the WAN port on the AirPort. This is the best way by far to set up the AirPort on any network since there will be no signal speed loss over the Ethernet cable....up to 300+ feet, or about 100 meters.

If you cannot run the Ethernet cable from your main router to the location of the AirPort, you might want to try a pair of Ethernet Over Powerline (EOP) adapters....also called HomePlug adapters.....to send a signal over the AC powerlines. The theory with these devices is that you already the wiring in place, you just need the adapters.

In practice, things do not always work as well as the theory might suggest......after all, you are trying to send a very low voltage signal over very high voltage powerlines......so if you decide to try a pair, it would be a good idea to understand the store's return policy.

1) Apple has created a router/storage device that would only extend an existing home network if paired with another Apple router.

Correct, if you want to "extend" using a wireless connection between the AirPort devices. Not correct, if you "extend" using a wired Ethernet connection.

2) Apple has created a router/storage device that has to be the MAIN router in the house, or it won't work as intended.

Not Correct. The AirPort can be the main router, but it does not have to be.

For example, if you have another router set up now, the AirPort can be set up to operate in Bridge Mode, (a configuration wizard will basically do this for you) so that it becomes a client on the network. Your current router will continue to perform the same functions that it does now.

The AirPort can perform as a wireless access point and provide a wireless signal....if you need it....or, the wireless function can be turned off and AirPort will function as a wired hard drive. The Ethernet ports on the AirPort are enabled either way.

Setting up the device in bridge mode through another router means that the hard drive will only be accessible to other devices on the network through wifi.

Not correct.

Wired devices can connect to your current router.....or.....they can connect to any of the LAN <--> ports on the AirPort.

Remember......your router and the AirPort will be on the same network. It does not matter whether devices connect using wireless or Ethernet. They will all receive IP addresses on the same subnet.....since they are all on the same network subnet.

The AirPort configuration tool has "Connection Sharing: Off(Bridge Mode)" greyed out on the Internet tab and I can't make any other selections from the pull-down.

You will need to reset the AirPort back to default settings and then set it up again. This will not affect any backups that you might have already done.

We'll provide the steps, but we need to know if you want the AirPort to provide an additional wireless network signal, or whether you don't need the AirPort to provide wireless service.

You will need to have an Ethernet cable that will be used for the setup and it must remain permanently connected between the router and the AirPort.

You are not using the correct steps. We were discussing configuring the Time Capsule to create a wireless network.

Do you want the correct setup? If so, please answer the question that we asked above about whether you want the Time Capsule to provide a wireless network or whether you don't need that service.

Another potential issue here......IF.....you have a new Time Capsule, it appears that you are trying to use an older version of AirPort Utility to configure the AirPort.....that does not meet the requirements for the new AirPort Time Capsule. I'm not sure how that might be affecting things.

Here are the System Requirements for a new AirPort Time Capsule:

Setup and Administration

iPhone, iPad, or iPod touch with iOS 6 or later and AirPort Utility 1.3

or

Mac with OS X Lion v10.7.5 or later and AirPort Utility 6.3 or higher

(It appears that you may be trying to use a 5.x version of AirPort Utility.)

http://www.apple.com/airport-time-capsule/specs/

Bob, Airport utility is updated with the latest version.

There is no setting for Connection Sharing on a 6.x version of AirPort Utility that I can find anywhere.

There is a setting for Connection Sharing on an older 5.x version of AirPort Utility, which appears to be the version that you are talking about.

Please open AirPort Utility and click on the AirPort Utility menu in the upper left corner of the screen. Then, click About AirPort Utility.

What version number do you see?

2) I DON'T want to provide a wireless network. I want to be able to use the higher bandwidth ethernet ports and access the hard drive.

Thanks for the information. We will not set up the Time Capsule to provide wireless at all. It will be a wired hard drive, once we get clarification on what version of AirPort Utility that you are using.