If Microsoft Office-products (or some other Windows applications) give an error message that you are offline while connected, it's possible you're afflicted by a Windows bug caused by the way Windows checks if you have an active connection. To solve that issue, follow these instructions:
- Open the settings for your network adapters (you can do that by searching for ncpa.cpl in the Windows menu). You will see a network adapter called TAP-Windows Adapter V9 which is the one used for your VPN connection.
- Right-click on the TAP adapter and select Settings
- Select Internet Protocol Version 4 (TCP/IPv4) and click on Settings
- In the new window that comes up, select Advanced at the bottom
- You will see an alternative that says Default gateway; press Add and enter the IP address that your router use (for example, 192.168.0.1)
- Save the change
If you are unsure what IP address to enter in step 5, open the command prompt in Windows and type ipconfig. The IP address is the one displayed as Default Gateway (Wi-Fi in the below example):