When the sync works after entering the IP and port manually, the problem seems to be Bonjour, the service that does the IP/Port configuration automatically. The USB connection cable is not necessary, because syncing will still happen over WiFi after entering the port and IP. So the firewall actually seems to be the root of the problem. Disabeling the firewall completely is not necessary, but you can check the firewall configuration. Normally there is an option to add certain programs to a white list. After adding the Divelog.exe file to the list of allowed applications, the firewall should no longer block the device IP/port lookup.