Hello Cosine64,
Many thanks for your prompt updates with above information. If other users who use the same email service are having the same problem and this issue related with your ISP service provider, please kindly contact them to further confirm the status of this issue and request further assistance.
Besides, regarding your concerns about the More settings option in Outlook, the interface has changed and you may try the following steps to check the result: on the Account settings window, choose your IMAP account and click Repair > Advanced options and select the checkbox before “Let m repair my account manually“ > click Repair, then you will be able to edit the Incoming server and the Outgoing server settings for your IMAP account. For your reference: