From your Roku home screen, click on Settings, then Network, and then Repeat Guided Setup. If this process solves the issue, the Roku's setting were likely causing a data retrieving problem. If the Roku is still having trouble after completing those steps, the problem more likely involves your Internet speed or the strength of your wireless signal. Roku offers additional customer support at 888-600-7658.
Contact your Internet provider if you still have problems with the Roku. They can tell you if they are having any service problems that could be affecting Roku streaming. Try streaming other programs as well. If they stream fine through the Roku without any retrieval problems, the problem is likely not the Roku device itself, but rather than individual channel the original program is streaming through.
The hours of 7 p.m. to 9 p.m. tend to be the busiest for Internet traffic, so you are most likely to experience Roku streaming problems during that time period. Conversely, 2 a.m. to 3 a.m. tends to be the slowest, so the Roku shouldn't have any streaming problems at that time if it and your Internet connection are working properly.
Unplugging your Roku is another way to solve potential problems with the unit. Unplug the Roku and the router, wait 30 seconds and plug them back in to restart them. If the Roku is having problems, this often resolves them.