Pairing an old Apple Watch

Hi there!

Trying to pair an old Apple Watch that I haven’t used in years to my iPhone 13. When trying to pair it’s sAying I need to get a software update. After clicking get update it reads me a message saying I’m not connected to the internet and doesn’t work from there. I am connected to my home wifi.

Help? I’ve turned my phone on and off, reconnected to wifi several times to no avail.