What is their network speed? How many people use this network at one time? Just wondering if this is a bandwidth issue.
Their internet connection is 1Gb? Is this a business or a residence? I guess I don't too often hear of Gb internet connectioms, at least where I'm located, unless it's a business.
I have residential 1gig available here with Suddenstink but only pay for 400 mbps. I had this issue until I reconfigure my router to use 2.4 GHz. Less crowded than 5GHz. Stream flawless now.
I have a Belkin router with wifi turned OFF: Netgear FS105 switch; Premiere+ and Roku 2 (4210) connected to the Netgear switch; and 1.31 Mbps DSL ($71). I have SD Netflix subscription and rarely see that 'try again later' phrase, a second try 5-seconds later usually gets the Netflix show running.
Did you remove Netflix app - Reboot Roku - install Netflix app (re-enter email and password).
They aren't trying to use more Netflix streams simultaneously than their Netflix subscription allows are they?
Maybe they didn't exit Netflix apps on 4 or 5 of their devices?