Hi,
It sounds like Outlook is just getting a bit confused with your account. Sometimes it keeps old credentials around, so it’s worth checking Windows Credential Manager and clearing any saved passwords for that email, then restart Outlook and see if it helps. Also, make sure your email provider is okay with IMAP/SMTP access, and if you’ve got two-factor authentication on, an app-specific password might do the trick. Occasionally, the Outlook profile itself can get stuck, so creating a fresh profile and adding your account there can solve a lot of headaches. And even if your firewall seems fine, some antivirus software can quietly block things, so temporarily disabling email scanning and double-checking the IMAP/SMTP ports can sometimes get everything talking again.
Kind regards,