We are using Exchange 2016 with Outlook 2010/2013. In Outlook connection status window I've noticed that it has failed connections to our intranet Exchange 2016 server using it's External URL address.
Server is reachable through it's Internal URL and connects OK, it's subnet within same site with clients so I have no clue why would it try to go through External address in a first place.
So any help is appreciated.