Hulu will stop working on these older players after June 24
ArsTechnica recently noticed that a handful of Roku devices will no longer support Hulu service starting June 24. Among the future unsupported devices, the Hulu support pages mention the Roku Streaming Stick models 3420 or earlier, along with Roku Streaming Player models 2400 up to 3100.
Hulu's decision to require these older Roku devices makes sense though since they were only able to run the classic version of the app in the first place, which didn't support live TV and other resource-hungry features.
In order to be able to keep using Hulu, you'll need one of the modern Roku devices that will continue to support the app even after June 24: Roku Ultra, Roku Premiere and Premiere+, Roku Express and Express+, Roku 3 and 4, Roku 2 (model 4210), Roku Streaming Stick (model 3500 or later), Roku TV, and 4K Roku TV.