OK...I got Active Sync working on my new 2010 Exchange server and moved the users who use it over to it. I'm finding now that when they are on the office wifi they can't connect but if they switch it off and connect with 3g it works.
It seems like wifi works but not from within the office.
Worked fine on the wifi when we connected to the Exchange 2003 server. Essentially the only change I made was to redirect ports 80 and 443 from Exch2k3 to Exch2010. This has worked in every way except with the wifi access from inside.
Also, I don't know that it would make a difference but the server name
Internally it's mail.domain.local
externally it's mail.domain.com
Can't see how that could be a bad thing though.