In you second paragraph, you mentioned about issues with Basic authentication if the DC is not available.
This must also be like this, because internal atuodiscover will also be provide by SCP (Service Connection Point) with is defined in AD under the CAS Server. If you are connecting from internal LAN, the other authentication methods are not disabled, which means, Windows Integrated authentication on the internal URL are still active. Click the contact or group you want to see the conversation history for.
In the sidebar, the Recent section lists new contact requests, unread conversations and conversations you've had in the last 12 hours (you can change how long chats stay in the Recent section in your settings). When I login to the Skype for Business app from my Mac, I cannot see my meetings nor attend them as the meeting tab says ' Sign into your Exchange account to see your upcoming meetings' which I have done several times.
