On-Prem Exchange to O365 – Outlook Issue

Hi all Last week we had a migration from On-Prem Exchange to O365. We had some issues connecting to O365 mail accounts (timeout, Autodiscover issues, etc.). So be sure to check following settings: Possible solutions Check possible hosts Рfile entries (C:\Windows\System32\Drivers\etc) Clear Microsoft Windows Credentials Manager for possible Outlook Рentries Delete Autodiscover registry key (HKEY_CURRENT_USER\Software\Microsoft\Office\x.0\Outlook\AutoDiscover) Do it for all possible Versions 15 / 16 / etc. We spend hours on this issues. Maybe it helps someone out there. Regards