My apple TV locates my network but then won’t let me enter the password. Instead I get a (-100) message.

Do you have the Apple TV box? Which model?

Identify your Apple TV model - Apple Support

Find your Apple TV model number - Apple Support

1. Try the steps as mentioned in: If your Apple TV can't connect to Wi-Fi - Apple Support
2. Try the ‘Other…’ option instead of selecting a listed discovered network. Especially if the password has been changed on the same network name.
3. For Apple TV (4th generation or earlier), verify that the router or access point isn’t set to use WPA3, as only device models from ~2018 or later support that. Instead use ‘WPA2/WPA3 Transitional’. Some users report having to set ‘WPA2’-only first.

What does the iPad have to do with it?