I have an Office 365 ProPlus licence provided by my university, and whenever I try to sign in to any of the Office 2016 products associated with this, I'm faced with error message 0xCAA70004, "You'll need the Internet for this", regardless of my connection status.
My very first thought was that I may need to use my university's VPN for the initial authentication (as the detailed error message talks about connecting to the required services), however this proved fruitless.
I then briefly searched online and begrudgingly accepted that reinstalling might resolve the issue, so I uninstalled, cleaned up any leftover registry entries (as I had read these could be a potential cause) using CCleaner, then reinstalled Office from my Office365 account online. The issue persisted.
My OneDrive account, however, is happily signed in and functioning. None of the Office apps will recognise that it's there, but it is signed in and I can use it from File Explorer.
I then found an article talking about using the Microsoft Support and Recovery Assistant for Office 365, which I downloaded and signed in to. This declared that I wasn't signed in to OneDrive for Business, so i followed the on-screen prompts and tried to sign in (bearing in mind that I was already signed in). The sign-in failed, and the tool exited.
When I look at my Office365 account online, it registers the install on my laptop and shows the install date as date of my reinstall a few days ago, and I have no sign-in issues at all online.
I then thought it could be my Bitdefender security software causing an issue, so I temporarily disabled the firewall on it and tried, which also failed.
I'm at a loss on what else to try, and I can't find any reports of it in anything other than Outlook 2013 with the same error code. Can anyone suggest a fix?
Specs:
Microsoft Office 365 ProPlus 16.0.8431.2215
Windows 10 Home, Version 1709, Build 16299.125