Mark,
I sounds like a bandwidth / throughput issue possibly with your ISP or router. Have you run a Speedtest from a site like "Speedtest.net. You might also try rebooting your Modem/Router, this can ofter speed things up.
We've done numerous tests here and have not been able to duplicate this hang on the "Downloading File Manifest". All update we run either from Wi-Fi or through iFly Connect are working just fine.