My stream arrived today. Setup was straightforwarded. Every show on every device (2 iPhone 5's, 2 iPads) is plagued by constant buffering - like stopping every 5 secs for 3 secs or so. Premier XL4 is connected to router via CAT5; same for Stream. I don't know how to directly measure WIFI speed within my network, but all devices connect over WIFI to the internet and Speedtest reports 18-25Mbps, so doesn't seem to be a WIFI problem.
Have rebooted XL4 and Stream. Stream S/W version: 19.1.1-01-6.
What else to check?