Can I use Extreme with Time Capsule to extend my gateway router and still use Capsule as "external HD"?

Question

Bought Airport Extreme with Time Capsule version 7.7.2 with 2 Terabytes Feb 2014. It was probably an expensive mistake, but after searching for weeks for a external hard drive, it seemed reasonably priced to just use the capsule as my external hard drive for the price I paid. Spend an hour with Apple Care to get it working-had to use ethernet cord to my iMac OS 10.8.5 processor 2.5 GHz Intel Core i5. I did not "need" the airport as we have a Winstream SAGEMCOM modem/router (Sagemfast 1704) But, I was desperate and about to lose my old external hard drive with literally had 3 computers worth of information on it. It had already "died" once, but got it back, so once I got the airport/capsule and was told I just paid for an expensive HD, I had no time to take it back to get something else-I had to transfer my info right then. We (Apple Care) could not get it to work as a HD wirelessly. It may be because it was being set up for the first time; I don't know. I was hoping I would get a transcript of all done so I could do it myself if needed later on, but when I looked at my email-they didn't do that. (Don't know if that is normal, I was used to other "techs" sending the email.) So now I really want to try to move my airport and "extend" our wifi as it said on the "box" that you could do...
Our Windstream router had to be placed in the lower level at the bottom of our stairs. The stairway is "open" (no door going down the steps). I want to place the Extreme at the top of the stairs so that we can use some things in our offices or not have Netflix on our TV lose connectivity when we all are on our computers.
I know I need an ethernet cord to connect directly with the modem/router to the Airport Extreme.  I don't know what I will need to do after I connect it as it was so goofy when we set it up the first time (With the app it would disappear and not show up..) But my biggest concern is will I be able to still use the capsule as my hard drive and will I be able to do it wirelessly? (Even with it connected by ethernet, every day I have to re-connect to it before I can click on anything on the hard drive. It never shows up on it's own as my old HD did. That drives me nuts.) I do back up using the Time Capsule feature as well. I appreciate any help.

Answer 1

I am still willing to plug in the ethernet cord to the modem/router and try it IF I was able to get a step by step instructions..
Connecting the Time Capsule (TC) to the existing Winstream by Ethernet would be the basis for a roaming type network. This type of network allows you to basically "roam" with a wireless client and connect to either router. This, in essence, would provide you with an "extended" wireless network. The Apple routers can work with just about any manufacturers' routers in this fashion.
The keys to having a successful roaming network are as follows:
The routers must be interconnected by Ethernet.
Both routers will broadcast their own Wi-Fi network, but MUST use the same Network Name (or SSID), wireless security type (WPA or WPA2), and wireless password.
The TC MUST be reconfigured as a bridge.
Connect a single Ethernet cable between one of the Winstream's LAN ports and the WAN (circle of dots) port on the TC.
The basic steps are:
Power-down the Winstream.
Perform a "factory default" reset on the TC. Leave the TC powered-down after the reset has completed.
Connect the TC to the Winstream using an Ethernet cable.
Power-up the Winstream. Wait at least 10-15 minutes to allow it to initialize.
Power-up the TC. Wait at least 5 minutes to allow it to initialize. (Note: Since we just reset the TC it will be performing as a wireless router that will be broadcasting an unsecured Wi-Fi network with a Network Name of something like: Apple Network NNNNNN)
Connect your computer to the Winstream's Wi-Fi network.
Run the AirPort Utility. select the TC, and then, select Edit.
Go to the Network tab.
Change the Router Mode option to: Off (Bridge Mode)
Select the Wireless tab.
Verify that the Network Mode option is set to: Create a wireless network
For Wireless Network Name, enter the Wi-Fi network name used by the Winstream.
For Wireless Security, select the equivalent security type that is used by the Winstream. (Note: Use "WPA/WPA2 Personal" if the Winstream is using WPA/TKIP. Use "WPA2 Personal" is the Winstream is using WPA2/AES.
For Wireless Password, enter the same password used by the Winstream.
Select Update and allow the TC to restart.
As far as your external HD, yes you should still be able to use it as before.