ActiveSync is a wonderful thing — unless something goes wrong.\u00a0 In the maddening manner of most Microsoft error messages, you get the functional equivalent of “something went wrong” with no other detail — and worse, an error message that appears to be telling you something:<\/p>\n
“Critical communications services have failed to start.\u00a0 Try resetting the mobile device, and then connect again.”<\/p>\n
This might lead you to conclude that the issue is on your mobile device, when in fact, it appears to mean nothing of the sort:\u00a0 it appears to actually mean, “ActiveSync didn’t receive any communications from the device” which is just as likely, if not more likely, to be a problem on the PC side.<\/p>\n
ActiveSync communicates on these ports:<\/p>\n
TCP from Mobile Device to PC:\u00a0 990, 999, 5678, 5721, 26675
\nUDP from PC to Mobile Device:\u00a0 5679<\/p>\n
So you can start troubleshooting by making sure these are open and available on the PC.\u00a0 (If you have a “personal firewall” on the PC, start there.)<\/p>\n
In my case, I finally traced it to Winsock2 corruption, as explained here<\/a>.\u00a0 Something I’d installed or deinstalled apparently managed to leave a wake of destruction.<\/p>\n The solution was to open a command window and execute “netsh winsock reset”, then reboot.<\/p>\n","protected":false},"excerpt":{"rendered":" ActiveSync is a wonderful thing — unless something goes wrong.\u00a0 In the maddening manner of most Microsoft error messages, you get the functional equivalent of “something went wrong” with no other detail — and worse, an error message that appears to be telling you something: “Critical communications services have failed \u2026 Continue reading