My roku 2 model 4210X was put in service November 2015. It has started to cut out and not work properly. Is it just too old or can it be updated?
The Roku 2 (4210) is a bit older, but it is still supported and updateable to run the current version of Roku OS.
(https://developer.roku.com/docs/specs/hardware.md)
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However, you would probably find that one of the currently available models may perform faster and better for you with the newer processors, memory, and technology. Another consideration is that as the devices get older, some channel developers begin to reduce their support and availability to them.
Any model besides the standard HD Roku Express (non-4k model) would likely give you improved performance depending on your streaming needs and budget.
(https://www.roku.com/products/players)