Q: Do I need to have cable to use a wifi router?

Hey Ken2sons,

Welcome to Apple Support Communities.

From what I gather, you want to know if your iPad Air can use Wi-Fi to connect to a local-area network which doesn’t have an active Internet connection. It can, take a look at the article below for more information about joining Wi-Fi networks with iOS devices.

iOS: Connecting to Wi-Fi - Apple Support

Cheers,

-Jason