Roku Soundbar turns offafter about 4 hours of continuous play. Any suggestions?

Cofield 

There is a "Bandwidth Saver" feature on Roku devices that deploys after 4hours to cease data usage when enabled. (note: some channels/apps have their own similar feature as well that may not be able to be disabled even when the Bandwidth Saver on Roku is disabled in the Settings).

Try disabling Roku's Bandwidth Saver from Settings/Network/Bandwidth Saver and see if that helps you. 

https://support.roku.com/article/360037927713