Outlook office 2021 problem with Windows 11 computer account

1. Restart Outlook 
Close Outlook completely (end all Outlook processes via Task Manager) 
Re-open for testing 
2. Check account status 
Open Outlook → File → Account Settings 
Check that the account shows "Password Required" or "Disconnected" 
Click on "Repair" or retype the password 
3. Repair the Office installation 
Control Panel → Programs and Features
Find Microsoft Office 2021 → click on "Change" 
Select "Quick Fix" → wait for it to finish and restart your computer 
4. Rebuild Windows credentials 
Open Control Panel → Credentials Manager 
Access Windows credentials 
Delete all credentials related to Office/Outlook 
Restart Outlook and log in again 
5. Create a new Outlook Profile 
Control Panel → Mail 
Click on "Show Profile" 
Select "Add" → Create new profile 
Re-add mailbox account → Set as default 
6. Check the account type 
If it is an Exchange account: 
Ensure that you are using the "Microsoft Exchange" connection method 
It may be necessary to manually configure the server address 
If it is IMAP/POP3:
Check if the server settings are correct 
7. Windows 11 specific check 
 System compatibility check 
Right-click Start Menu → Settings → System → About 
Verify that Windows 11 version is 22H2 or newer 
Check for Windows updates to be installed 
12. Disable security software for temporary testing 
Temporarily disable Windows Defender firewall/third-party antivirus 
Testing Whether Outlook can connect properly 
13. Completely reinstall Office 2021 
Uninstall Office 2021 via Control Panel 
Reinstall using installation media or official website 
Run as administrator on first startup