Hi @Florian Marquardt ,
Welcome to the Microsoft Q&A platform!
Based on your description, you are dealing with an issue where you cannot sync your account through Exchange. Here are some things you can check and try:
- Since you recently switched to using an authenticator app, make sure all your devices and clients are compatible with 2FA. Some older clients may not support modern authentication methods. You may need to create an app password specifically for these clients.
- Double-check the server settings you are using. The URL https://m.office.com:443 should be correct, but make sure there haven't been any changes or updates to the server settings that could affect the connection.
- Sometimes problems can arise if there is a mix-up between personal and work/school accounts. Make sure you are using the correct account type for each service. If your private email is linked to both personal and work accounts, this can cause conflicts.
- If you are unable to remove the mobile device from your account settings, it could be due to permissions or sync issues. Try accessing your account settings from another device or browser to see if that helps.
Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.
Best,
Jake Zhang