Hi Fernando, “These ones” doesn’t sound natural to me. Just “these” is clear enough. But in this case the objects you are talking about are further away, so use “those”. I would rephrase the sentence to “As you know, the update didn’t work for those.” The information in the entire sentence is old information, so the clause saying so should go at the start.

I would put a comma before and after "as you know" but otherwise it is grammatically correct but not very clear. "We still have some machines running windows 7 because the update didn't work for them," is how I would phrase it.

Looks fine to me