Cant sign in to 365 - no internet error

Hello Shane S

I can see that your Microsoft 365 app said no network after MacOS update

Since your internet works normally and the same issue happens on Wi‑Fi and hotspot, this likely isn’t a general network problem.

It sounds more like Microsoft 365 for Mac is unable to reach the sign-in/update service because of a local macOS setting, cached Office sign-in data, licensing files, proxy/certificate settings, or a damaged Office installation after the macOS reset.

Since Q&A assist already provided several troubleshooting methods, I would like to add some additional methods for you to try:

Check Date & Time

• Go to System Settings > General > Date & Time.
• Turn on Set time and date automatically.
• Incorrect date/time can stop secure sign-in from working.

Remove old Office sign-in/licensing cache

• Close all Microsoft apps.
• Open Keychain Access.
• Search for and delete entries related to:
  • Office
  • Microsoft
  • ADAL
  • MSOID
• Restart the Mac, then try signing in again.

Feel free reply back to this post if you need further assistance, I'll be happy to help.

Follow these steps in order, testing Microsoft 365 apps after each major step:

1. Check for known sign-in fixes via update (macOS / Office)
   A similar issue on Apple devices was resolved by a new software update. On macOS:
   • Open System Settings → General → Software Update and install all available macOS updates.
   • After macOS is fully updated, open any Office app (for example, Word) and check for updates from the Help → Check for Updates menu (if using Microsoft AutoUpdate). Install all Office updates.
2. Verify general network connectivity for Microsoft 365 endpoints
   Even if general internet works, Microsoft 365 apps must reach specific services:
   • In a browser, confirm that sites such as www.msn.com load. If they do not, troubleshoot basic connectivity first (for example, using ping and nslookup as described in the network troubleshooting article).
   • If a proxy or security device is in use on the network, ensure it allows outbound connections to Microsoft 365 endpoints (for example, *.microsoftonline.com, *.sharepoint.com, *.outlook.com, *.lync.com, ports 80/443, TCP/HTTPS) without extra authentication.
3. Check firewall / proxy / security software for Microsoft 365 traffic
   Even with the macOS firewall off, third‑party security or filtering tools can block or mis-handle Microsoft 365 sign-in traffic:
   • If any third‑party antivirus, web filter, or security agent is installed, temporarily disable it and try signing in again.
   • If the environment uses an authenticating proxy or enterprise firewall, configure exceptions for Microsoft 365 URLs so that Office traffic is not intercepted or challenged for extra authentication.
4. Confirm account and license status (for home subscriptions)
   • In a browser, sign in to https://www.office.com with the Microsoft account used for the subscription and confirm that the Microsoft 365 Personal/Family subscription is active.
   • From that page, use Install apps to reinstall Office if needed (after the steps below).
5. Remove cached identity data (if repeatedly failing sign-in)
   If the device previously had different accounts or corrupted sign-in data, clearing cached identity information can help. On macOS, this is typically done by fully uninstalling Office and removing its identity/licensing data, then reinstalling:
   • Follow the guidance in How to remove Office license files on a Mac to remove existing Office license files.
   • After removing license files, reinstall Office from office.com and sign in again.
6. If the problem persists after updates and reinstall
   • Collect details (exact error messages, whether the browser can reach Microsoft 365 services, and whether other devices on the same network can sign in).
   • Contact Microsoft Support and reference that the issue started after a macOS reset and persists across different networks, indicating a possible interaction between the updated OS and Office sign-in components.

These steps align with known patterns where Office apps report “no network” or fail activation even though general internet connectivity is working, and where a subsequent software update or a clean removal of Office licensing data resolves the issue.

References:

• How to troubleshoot non-browser apps that can't sign in to Microsoft 365, Azure, or Intune
• Microsoft 365 Apps activation network connection issues
• Can't sign in to Microsoft 365 desktop applications
• Microsoft 365 Apps activation error: "There's a problem with your account"
• My Microsoft365 Office Package no longer works with my iPad Pro - Microsoft Q&A
• Can't sign in to microsoft 365 desktop apps - Microsoft Q&A
• MS365 products not signing in as even when internet connection is available - Microsoft Q&A
• How to fix the issue with MS Office asking you to log in every time you open an Office app - Microsoft Q&A
• Can't access Microsoft support - Microsoft Q&A