We have a customer with multiple sites, all the sites are connected by VPN. At one site we have two servers with Microsoft 2003 R2, one AD and one TS. On all workstations (XP and Vista) and the AD server we simply can connect to the exchange server with outlook. Just click on it and Outlook starts normally. Since a few months (5) we have problems with the connection from the TS server to Exchange. Sometimes Outlook 200x starts normally and you can use Outlook the whole day, sometimes Outlook waits for a period of 20 seconds and then the connections is ok and you can use Outlook the whole day. Sometimes the connection is not ok and the error message: Microsoft Exchange is not available is shown with the Retry, work offline, Cancel button. Sometime when you press Retry the connection works and sometimes you have to press Retry several times until it is working. This problem only exists on the TS and the time does not matter, all users are sometimes experiencing this problem.
Using OWA on the TS server is working fine, the connection is always working.
Ping the exchange server works perfect no drops.
Network card settings are the same as the AD server.
The AD server on the site is a global catalog server.
The Event Viewer does not show any errors related to connection problems or any similar errors.
What have we tried?
- Upgrade from outlook 2003 to Outlook 2007.
- Install a new (PCI) network card
- Re-install SP2
- Check the registry for the rpcrt4.dll settings for Outlook but these are correct.
- Try another connection on the switch
- Create a new profile within Outlook
- When using Network Monitor we can see some RPC errors.
On all the other sites the connection is working fine with Outlook 200x, no problems found.
I hope someone can help us with this strange problem and if you need more info I will gladly give it.