Problems with ActiveSync? Could be your personal firewall.

All of a sudden, my Verizon XV6700 Pocket PC Phone stopped synchronizing with my PC via the USB cradle. I’d had this problem before (twice, actually), so I figured that after the right combination of PC restarts and phone soft resets all would be well again. But not this time. I ran through the ActiveSync troubleshooter, but it just told me that the device seemed to be disconnected. Then I noticed a tiny link to the detailed log from the troubleshooter. Within the log, I found this helpful advice:

Unable to establish a connection between the PC and the device. Get up-to-date solutions to common connection problems. Please click the following link: http://go.microsoft.com/fwlink/?LinkId=65257

The linked article suggests four troubleshooting steps. I passed the first three. The fourth made me check my firewall settings. Unfortunately, the firewall I’m using (F-Secure Antivirus Client Security) is not one of the firewalls for which Microsoft provides specific assistance. But that suggestion was enough. I tweaked my firewall to allow TCP/IP communication between my desktop and my mobile device, and presto, I was synching again.

Now the weird part is that according to my firewall log, there is traffic going back and forth between my device and my PC on ports other than the ones specified in the Microsoft article. That article mentions inbound TCP ports 990, 999, 5678, 5721, and 26675. But I’m seeing traffic on 1900 and 5678 as well. Don’t know what that’s about … yet. I’m also not sure why my firewall decided to start blocking the synchronization on January 29th, after allowing it for months previously. I don’t recall changing any settings. Perhaps it was an automatic update to the software that plugged some holes and locked some doors that should have been left open.