Foolproof method on baking a potato?

I’m not sure what I’m doing wrong, but every time I try to bake a potato, it never gets fully fluffy and soft like I expect. Large a russet baking potato’s, poke holes with a fork, then wrap in foil and put it in a 400 degree oven for about an hour

The past 3 times I’ve tried this, the center of the potato is still kind of hard. The outsides are soft as expected, but the potato isn’t full “baked” through.

Do I just need to cook it longer? Hotter? Did I just have bad luck with old potatoes?