Just set up Exchange 2010 from Exchange 2003. All devices coonected fine to the Exchange server. Since upgrading connections are intermitent. I can log on with a device and all works fine. Then at no set time, I get a cannot connect to server error. This is common for all iOS devices. No problem with web acces or droid devices.
I have the same issue, but it's only when trying to access the global address book. Sometimes it works great, and other times I get server errors. It's a huge pain b/c it never seems to work when I absolutely need it.