Last week, Netflix announced that it was ending support for older devices from Samsung, Roku, and Vizio after December 1st, but it wasn’t clear exactly why those devices were losing support, besides the fact that they were old. And a Netflix support doc isn’t helpful, saying that the problem is due to “technical limitations.” But Netflix has shared a little more detail about those technical limitations on older Roku devices with Gizmodo, and it turns out the answer is quite simple: DRM.

Here’s what’s going on: Netflix has used Microsoft’s PlayReady DRM since 2010 so that it could more easily bring its streaming service to the loads of TVs, devices, and set top boxes you can find it on today while satisfying its content providers that their work wouldn’t get pirated. But because Netflix had already shipped devices like the affected Rokus with an earlier form of deprecated Windows Media DRM, they would inevitably get left behind if Netflix ever cut ties with the old DRM standard and if those devices couldn’t be upgraded to the newer PlayReady instead. Now, it has — and they can’t.

It’s not clear from Gizmodo’s article why the older Samsung and Vizio devices won’t be able to use Netflix, but we wouldn’t be surprised if it’s the same reason. We’ve asked Netflix if that’s the case.