Hello, hopefully someone can help with this very strange issue i'm having with outlook when connected over a VPN.
We have an exchange server setup at our main office and 3 remote sites that connect to our main office via site-to-site VPN's. When a host computer is connected at the main office, outlook works just fine (auto-discover finds profiles, everything connects, can send/receive email). Outlook Anywhere and Webmail are also working. However, if a user connects their laptop at one of the branch offices that has a site-to-site VPN and opens outlook it tries to connect for a while, then says disconnected. If you try to setup a new profile, outlook auto-discovery will find the user account like it should. Then when it goes to the next screen to configure everything - the network connection test passes, the finding email@example.com settings passes, but then a message comes up saying "The connection to MS Exchange is unavailable, Outlook must be online or connected to complete this action" (during the logon to mail server step).
-We are using Exchange 2013 on a VM with Win Server 2008 R2 Enterprise.
-Host computers range from Win XP to Windows 8 (all are having this issue).
-Outlook on computers ranges from 2007 to 2013 (again, all are having the same issue).
-In the branch offices, the computers are using the DNS server in the main office for primary DNS.
-All computers can ping the exchange server over the VPN (by name and IP)
-All other network functionality over the VPN seems to be working (Network drives, Folder permissions, etc.)
-We have tried completely turning windows firewall off on the exchange server, no luck.