how do i undo forget this network on ipad air 3

You can remove all network information from your iPad by resetting your Network Settings:

Settings > Reset > Reset Network Settings

Alternatively, if you are within range - and can still connect to the WiFi Network that you wish to forget - you can simply forget the network from iPad Settings. While connected to the WiFi network:

Settings > WiFi > [Network Name / SSID] - tap the “i” icon - select Forget This Network

The “forget network” function cannot be undone. It doesn’t remove network completely though, just makes it so it doesn’t auto connect to it. To make it so it auto connects again, tap on it and type in the password.

Gruff2435 wrote:

The “forget network” function cannot be undone. It doesn’t remove network completely though, just makes it so it doesn’t auto connect to it. To make it so it auto connects again, tap on it and type in the password.

I have no idea what you are trying to convey, but at face value, this statement is entirely inaccurate and misleading.

Forgetting a WiFi network completely removes the WiFi network from the iPad - but to be able to use the “forget this network” function you must be actively connected to the specific network. Auto Connect is a entirely separate setting that control connection behaviour when within range of the network.

A “forgotten network” can be simply undone. Rejoining the network restores full network connectivity.

You can’t. The only way to get back on it is to select it and put in the password again. It doesn’t remove the network completely, it just makes it so I doesn’t auto connect.