Question about AirPort Extreme

Yes, download and install airport utility for windows.

Download AirPort Utility 5.6.1 for Windows

It will say it cannot setup AC wireless model Airport Extreme but in fact will work fine. Just click continue.

Mac is obviously built in.

I thought I was able to keep my current Linksys router and have the AirPort Extreme connect to it wirelessly.

Sorry but no .. that is not possible.

Although it seemed to work as long as my AirPort Extreme was connected physically via Ethernet cable, it stopped connecting.

It MUST use ethernet.. permanently. OR you can replace the Linksys or add in an ethernet connected airport Extreme or express. (IMO Express is a toy.. suitable for airplay and and small extra addition to wifi.. NOT for a network you rely on).

Now I'm trying to get the settings back to its original state, and I tried factory resetting as well.

Are you disconnecting the power.. holding in reset button .. reconnect power while still holding in reset until the front LED flashes rapidly..?? If not you have not actually reset.

I thought I was able to keep my current Linksys router and have the AirPort Extreme connect to it wirelessly.

Sorry, but Apple has designed the AirPort Extreme to wirelessly connect only to another Apple AirPort router.....an AirPort Express, AirPort Time Capsule, or another AirPort Extreme.

I used my iPad to try to set up and I selected to extend my wireless network, but from there, I kept getting "unexpected error" and was asked to try again.

Unfortunately, this would be expected since the AirPort Extreme is not compatible with a Linksys product for what you are trying to do.

so I created network name and password exactly the same as my currently ones as I remembered someone on YouTube said to do. Although it seemed to work as long as my AirPort Extreme was connected physically via Ethernet cable, it stopped connecting.

The AirPort Extreme might not have been set up in Bridge Mode, which is the correct setting when the AirPort connects to another router using an Ethernet cable.

Is there anything I can do to get it back to its original state?

Unless the AirPort Extreme is defective, a Hard Reset will erase all of the current network settings and reset the AirPort back to its original factory default settings.

Try power up the AirPort Extreme for a minute or two, and then hold in the reset button on the back of the AirPort for 7-8 seconds and release. Allow a full minute for the AirPort to restart back to a slow, blinking amber light status.

If the AirPort is operating correctly, it is now back to its original factory settings.

A Factory Default Reset will accomplish the same thing, but this is more difficult for most users. To perform this type of reset.......power off the AirPort Extreme, wait a minute, then hold in the reset button on the AirPort Extreme first while you then plug the power back into the AirPort. Keep holding the reset button for 7-8 seconds after to plug the power back in, and then release the reset button and allow a full minute for the AirPort to restart.

My new POS provider requires me to get the AirPort Extreme for the POS networking.

If this is really true, then you are going to have to replace the Linksys router with an AirPort Extreme. Then, another AirPort Extreme could be added to wirelessly extend the network that the first AirPort is providing......although it would be better if you could permanently connect the second AirPort back to the first using a wired Ethernet cable connection.

I tried the reset as it was instructed but same

Did the front LED flash rapidly? If not as Bob indicated it is defective. They have not connected the reset correctly at the factory.. the build design of these is terrible.. and we always see a bunch of failures of front led, reset or fan.. because they are all separate wires that need to be connected at the end of assembly.

Take it back to Apple for checking / Replacement.

That is correct. And if it flashes rapidly you have definitely reset.

After a reset with the airport plugged into power only.. no wired LAN or WAN connection.. you should be able to access it from iPad.. if it fails delete all the existing wireless networks.. reboot the ipad and try again.

Personally.. configuring wireless over wireless.. is much akin to those cartoons of the guy sitting on the branch he is cutting off.

I would use ethernet to configure the airport extreme.. it is much more reliable using wired than wireless connection.

If you have a Mac or even a PC available with ethernet it is going to get around whatever wireless issues you are having with the configuration.

Take the AirPort Extreme that you have now back to the store for testing. If it won't reset....it is defective.