To add to my thread, our office also uses Samsung Galaxy 10.1 Tablets (software version 3.2) and those tablets do not sync with Exchange when connected to the office Wi-Fi network either. Though the tablets do not generate a connection error as the Droid X phone does and the e-mail appears to sync correctly but no new e-mail is deposited onto the tablet. The only way to receive the most recent e-mail on the tablet is to switch over to the 4G network.
To further add to this thread, the IPhone does appear to have connection issues when using the office Wi-Fi and attempting to sync with Exchange. They apparently are not as often as with the Droid X, and sometimes the IPhone will synchronize, but connection issues do occur. Again, when the IPhone is switched over to the 3G network, the synchronization happens without issue.
And to add to our network information, the two wireless routers are not connected to the Exchange Server or any other network device. They are connected directly from the patch panel to ports on the the firewall so I do not believe any filtering device is blocking the synchronization.