I'm going to ignore any fool who suggests that I should check my internet connection.
I've been using Norton for years and have only ever been able to sign in (from the windows app) once. Everything else works (including updates etc). I can sign in via the website but never withing the app itself.
Could you provide a little more background info, such as your OS / latest update version, how long has this been going on, current Norton Product in question, any error codes or pop ups, are you having this issue when trying to sign-in through the product UI, Mobile Device, Password Manager, or My Norton online Account?
So the current patch Norton Security 22.20.5.39 for Windows should solve my signing in problems. Im still stuck with this sign in glitch. Not only does it not let me sign in but i get a 90 min block to go along with it.
Have you tried a remove only scenario using the NRnR tool and then downloading a new copy of your product from your My Norton Account and reinstalling?