When Outlook Anywhere stops working

So where do you start looking when Anywhere HAS been working fine now stops? I had this case today on a server with and 2 deployed. The remote outlook clients were receiving mail, but calendaring and GAL lookups failed. Turned out that the RPCPROXY key was mangled. Thanks to Riccardo Moretti for pointing me in the right direction.

The exact key location is HKLM\Software\Microsoft\\RpcProxy - ValidPorts

The value of ValidPorts had changed to an unexpected one. Trying to understand why I found some interesting articles here:

How does Outlook Anywhere work (and not work)-


Ultimately I fixed this by disabling Anywhere, Reinstalling over HTTP, re-enabling Outlook Anywhere.

After that I monitored the ValidPorts key to make sure it was populated properly and restarted Services after ensuring the RIGHT values had populated.

I'll try figure out why the key value changed in the first place and update when I know.