Your sandwich loaf runs 68 to 72 percent hydration. These bagels run 55 to 60. Montreal is the driest of the four.
So the dough comes together stiff, tight, and a little unfriendly. New bakers almost always add water right here, and that's the mistake. The low hydration is exactly what gives you the dense chew. A wetter bagel is just a roll.
If your mixer sounds like it's working, that's the right amount of working. Ten to twelve minutes on medium and you'll pull a windowpane out of it.