Using Ethernet to access internet for iPad Air 2

Clearly having an internet connection does not necessarily indicate that WiFi coverage is available. There are many situations where an Ethernet connection is available in absence of WiFi connectivity.

Assuming that your iPad has a Lightning port (such as your iPad Air2), you will need an appropriate Lightning to Ethernet Adapter:

• Belkin Ethernet + Power Adapter with Lightning Connector

https://store.apple.com/uk/xc/product/HMJU2ZM/A

If you have ethernet then you probably also have Wi-Fi. They both come from your router.