I’ve found there is neither rhyme nor reason for Outlook having difficulty connecting to Exchange over RPC. Many times the same configuration will result in errors or unpredictable behavior. It is frustrating to say the least. There is a decent work-around that alleviates most connection problems, especially the dreaded first attempted connection error. Below are the various errors that you may receive, and the fix.
The action cannot be completed. The connection to the Microsoft Exchange Server is unavailable. Your network adapter does not have a default gateway.
Outlook cannot log on. Verify that you are connected to the network and are using the proper server and mailbox name. The connection to the Microsoft Exchange Server is unavailable. Your network adapter does not have a default gateway.
Cannot start Microsoft Office Outlook. Cannot open the Outlook window. The set of folders cannot be opened. The attempt to log on to Microsoft Exchange has failed.
- Open the registry editor (at the run box type: regedit).
- Locate or create the following key: HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\RPC
- On the Edit menu, click New and DWORD value.
- Type DefConnectOpts and press ENTER.
- Right-click on DefConnectOpts and set the value to 0 if it isn’t already.
- Exit the registry editor and Outlook should connect to the Exchange folders now.