Have a SBS 2011 that I no longer can Connect Outlook over http to.
Found that we also could not Connect to https://domain.com/owa
We could Connect to https://domain.com/remote and than click on mail, that took us to /owa.
But not directly to OWA, that would only show a blank page, no error.
Changed Authentication from formed based to to basic (tried With and without Integrated Windows Auth)
Ran IISreset and now we can Access OWA.
But still not able to Connect Outlook 2013 over http.
testexchangeconnectivity.com gave the error "Exchange ActiveSync Returned an HTTP 500 Error"
(Mobile sync Works fine.. And now also OWA again.)