Miscellaneous topics that do not fit into specific categories.
The mailbox timing out after sign-in is related to a service issue Microsoft is currently experiencing with Outlook today, and many users are unable to access their emails at the moment, this is not a problem with your account.
You can follow the updates on this issue here: Microsoft 365 Status and https://status.cloud.microsoft/ (this page is loading slow).
I suggest waiting a few hours and trying to open your mailbox again.