what actually works to descale nespresso machine?

Which machine is it, Original or Vertuo? The routine is the same either way: empty the capsule bin and drip tray, fill the tank with descaler and water, put a mug under the spout, start descaling mode and let it pump through. Then rinse the tank and run a full tank of plain water through to flush it. The bit that differs is how you get into descaling mode, it's a different button combo on nearly every model, so check the manual for yours. Skip vinegar. It's slow on scale, can be hard on the seals and the taste hangs around for days. Citric acid or any proper descaler works fine, it doesn't have to be the branded sachets.