I too seem to be having this issue. I am running Windows 10 (Insider) release 14959.rs_prerelease.161026-1700 and Office 2016 version 1610 (7466.2023).
I have been having this problem for sometime now, and until today had not realized the culprit. What triggered my realization is that, due to compatibility issues with the last few Insider releases, I have not had Malwarebytes installed, and I never had any issue with Outlook during that time. I recently tried to install MBAM after the latest insider build update, and it installed OK - and my Outlook problems are back.
No real symptoms except that Outlook goes offline for my Exchange account. My outlook.com email continues to work fine, and I am able to browse the web. Interestingly, I am unable to browse to the Office365 Outlook Web Mail page during this outage also.
Please remedy this!
Thank you.